I don't have all of these devices (however I do have many - why do you think I could get you a list so quick?) and not all of them do everything that has been mentioned here. However I tried to keep most items linux based for you. The Divx thing is a perfect example also being all linux. Hell even the crappy Linksys Share thing I bought for dirt cheap can be seen by all my other devices (which means it has shares opened up).
I don't think you need to make desktop software to mount network shares, however if you think that your company is not funded enough to be secure in using something like Samba or whatever these other guys are using, then I think you should write one for the PC and one for linux (if it's even needed there).
Given the option of having no way to play my media from all my other devices (of which many are linux based like the Linksys stuff I think and HP Printer), or having to load a small "driver" on my PC to allow sharing. I would choose to load the driver. So long as you can load a list of the items in a shared directory and pick to either play, or show (slideshow) the items in the list I think it would be fine. Basically Chumby needs a Media Player.
This seems like such an obvious thing these days. Media devices have access to things on your network, period. What good are they if they don't? It seems you are trying to make the Chumby part of my digital life at home, so this is just an obvious thing IMHO.
Why can my Picture Frame do it, but my Chumby (which I paid more for) not?
Once again - this is your company - if you don't see this as something as a must and obvious should-have, then you should really get out from under your desk and look at the CES landscape a bit. You want to sell units, your mass market will expect this stuff. As merely a customer, take it for what it's worth. Also, answer to me a question I ask myself all the time: "Why can I pick files off my Linksys USB hub and play or view stuff which cost like $30 and is viewable by everything, yet I can't do that with my Chumby which I paid $175?"
Being as small as you make out to be, I think that "going to higher-ups" should be like a little meeting in a small room so it's not like going to the board of IBM or something here! I could be wrong, but if I was, I think we would not even be having this discussion.
I gave you a list - work with it! Why is it that I knew even when I took my time (very expensive time at that - I would have rather taken my kid for a ride in my Ferrari than type that message - yes I've done startups myself <g>) I would get a response like yours.