I have two here, both Ethernet versions.
One has been unlocked with a valid smart card and is fully functional, the other is functional but missing it's card and currently in the unused (waiting for a provider card) state.
It was probably me who started the thread you found, I was trying for a while to hack them into basic media players (they can already play a mp3 stream if fed a stream URL in the correct format, but they time out after 10 minutes of no button press).
Unfortunately I hit a wall when deciding that the only way I was going to get into the OS was to mount the Disk on Chip device on another computer and examine/modify the contents, sadly the only way I can find to do this is to buy a DOC development board that would provide a DOC to IDE interface. The cost of the board was more than the project was worth to me so I gave up.
Now I think that there are some MiniITX boards that have a potentially compatible DOC interface, this could possibly be used to interfere with the netgem's disk on chip.
I would still be interested in helping in a hacking project if you have any other ideas, As I say I have two netgem's with all the bits. I also have a digital electronics capable workbench complete with a very high spec reflow soldering station (you are going to need that to remove the DOC without destroying it or the PCB)
I also have my original notes somewhere, I think most of the useful information was posted to this list or various newsgroups but I'll try and dig it out and mail to you off list anyway.
W