Hey, the First 50 were (are) the original post-beta, but not quite gone gold Chumby recipients. They were chosen in a contest (many got to plead their cases, but only 50 were chosen... alas, I was not one.) and given a final hardware version (software, of course, was still fairly primitive) of the Chumby to play test at a discounted cost. It was about a month later that Chumby was opened for sale via invite, and then open for sale more widely for first people who were really curious about the tech and finally widely released on the public at large.
I guess the First 50 chumbys are identical to the ones they sell now, except for a "First 50" plaque on the frame of the touch screen.