Answered my own question

On a pc if you go to http://grove.monkeyradio.org it'll prompt you to save "listen.pls"

Open in in a text editor and it shows

[playlist]
NumberOfEntries=1
File1=http://76.73.3.245:6969/

SSH into your Chumby and enter and it works!
btplay http://76.73.3.245:6969/

M3U files are not audio files - they're a playlist of URLs (much like  PLS file) to the actual audio.

btplay only understands paths/URLs to actual audio files.

The "My Streams" section of the Control Panel understands what PLS and M3U files are, fetches them, and extracts the actual URLs and passes them to btplay.

I think Duane is saying that that won't work, if you're sending an actual path (not a URL) to the device then it requires an actual audio file.

That being said what if you did something like btplay http://127.0.0.1/mnt/usb/Music/Allsongs.m3u
The 127.0.0.1 is your device. No idea if this will work or not but its worth a try. I'll see if I can create an m3u playlist and try it out myself.

Ok so this doesn't work "as is" but I'm sure I'm on the right track. By default the device is running a webserver, httpd, but its only serving pages from /www/cgi-bin.

I stopped httpd and restarted it with httpd -h /mnt/storage/music/ which now should serve files from the music folder I created under /mnt/storage/music

I wrote an m3u playlist file (on the infocast to it has the proper carriage returns etc) and tested it under windows to confirm it works.

If I try btplay http://127.0.0.1/mymp3file.mp3 it will play the file but if I try the playlist file it does not work.

[Update]
After rereading Duane's post and reading more in the BTPLAY documentation I realize that it simply isn't possible. I misread Duane's comment about MyStreams recognizing a playlist when its presented as a URL and not a path, this is why I configured httpd to give it a URL. My mistake was that MyStreams is not BTPLAY so as Duane states it can only play actual music files or streams from an actual mp3 server.

So in short I don't think this is possible the way you want to do it, MyStreams is interpreting the playlist itself and the serving BTPLAY with the commands it wants to hear.

Oh well this gave me a chance to play around and learn somemore

Oh!  Oh, that script I think I might be able to do, indeed so.  I think I can do that.  I even think my "search for a file by name and play it" script might even have most of the components.

How do you monitor btplay?  What do you use?

Thank you!  Thank you!

Oh, I've read the wiki pages on btplay and audio; like I said, there are some things that I just don't KNOW, don't know how to use. 

I should mention that I'm a physics geek from the 90's; we learned FORTRAN by necessity, and bash scripting to make things more efficient, but all in a scattered and self-taught way.  I am not a computer geek, though I try to fake it ;) when I want to get something done.  Most of it's beyond me, and so I need to either be pointed in the right direction, or soemtimes even walked through it, before I can make it work.  I did try to use the wiki info on playlists and couldn't get it to work, but I don't know if that was me or the chumby.)

But usually, once you show me, I'll manage to hang onto it and make use of it.  For example, there's my song-shuffle cron jobs and "approximate random play" mp3 stream alarms, which I posted about here.  If I can get this working, I'll be happy to share it too, probably another update in the same thread, since it's still on the first page of this forum anyway.  I've wanted this since we got our first chumby several years ago; I can't be the only one :)

And I am eternally grateful for being  pointed in the right direction, too >grin<

Okay, how does one monitor a file?  I found the files in /var/run and I can see  how the contents of "/var/run/btplay.state" change when it is playing.  Is this a job for cron?  That seems kind of inefficient.

I feel the exact opposite way...

I'm just giving perl gurus a hard time.  I prefer bash/python to perl because I'm not very versed and perl can be really hard to read.  I'm glad somebody was able to help you get further with your task!  Hopefully it works great so we can all take advantage of the work done by your friend.

I'll update again if we get things more ironed out; for the moment, the problems that come up seem to be due to buggy btplay, not to the script.  Here it is:
http://lady-of-lothlorien.com/chumby/bin/play_list

To operate, feed it:

play_list [name of your file containing list of songs with full path] &

Other commands,

play_list --next 

play_list --stop

should be pretty self-explanatory, I think.

Don't forget you can use http://lady-of-lothlorien.com/chumby/bin/random_reorder to shuffle your songlist between playings.

If you need a reminder, you can get the scripts and make songlists and so on with the various below commands--which assumes you have your music files on a USB drive at /mnt.usb/Music:

 
mkdir /mnt/usb/bin/
cd /mnt/usb/bin
wget http://lady-of-lothlorien.com/chumby/bin/play_list
wget http://lady-of-lothlorien.com/chumby/bin/random_reorder
chmod u+x *

nano /psp/.profile [and add :/mnt/usb/bin/ to the end of your PATH]

cd
find /mnt/usb/Music/ -type f > /mnt/usb/Music/AllSongs.m3u [you only need to do this once]
random_reorder /mnt/usb/Music/AllSongs.m3u [you can do this any time you play your music]

play_list /mnt/usb/Music/AllSongs.m3u &

Would have been nice, easier, but didn't work.  Even if the m3u was already defined as a stream in /psp/url_streams and could be played from the control panel/music screen.  Copy/pasting the stream from /psp/url_streams (in case of typos) didn't work.  If you recall, trying to use streams from the command line somehow was what I was originally asking for.

http://wiki.chumby.com/index.php/Controlling_BTplay also claims that btplay has some playlist capability, but I couldn't get anything on there to work either.

But hey, that play_list script is working beautifully, aside from where btplay itself is buggy (and always has been, even when playing a single mp3 from the command line one at a time).

Your poor little infocast!  I guess setting up another, more powerful computer to do compiling didn't work out, huh?  Well, someday it'll be done

I'm sorry, I suppose it wasn't clear: I'd tried all of that *before*.  Yes, it would be lovely if it'd work that way, but no, it doesn't.  I also tried writing it into scripts that would do it for me with the filename as an argument in case that would convince it to see it as a stream, and all different varieties of types of quotes and even things like `cat [the m3u file]` (etc etc).

That's not to say I get errors or that it refuses to even try.  But if I enter, for example:

echo '<event type="UserPlayer" value="play" comment="file:////mnt/usb/Music/Garbage.m3u"/>' > /tmp/flashplayer.event
/usr/bin/chumbyflashplayer.x -F1

Then "more /var/run/btplay.properties" will tell me:

Tags/Title=Garbage.m3u

Which is to say, it tried to play a text file. 

And "more /var/run/btplay/state" returns a 1, which is "not playing anything."  It tried to play the m3u file, it couldn't, and it gave up.

I do suspect if there were some way to wrench this particular bit (sending a local playlist stream to the control panel) into a workable solution... that Duane would have mentioned it earlier in the thread when he replied.  Or that chumby tech support might have done so when I emailed them years ago asking for some way to play a playlist from the command line.