There are loads of these out there actually. I did some test work for a couple of similar products running Linux, but to be very honest, there still is a way to go before it can be the success as it should be. PalmOS by far is the best designed palm computing platform IMHO. The problem I see for Palm is that their pricing structure is pretty close to ridiculous, it doesnt cost that much for a PDA, I remember reading a slashdot article (try searching for it) that claimed that Empower Linux OS and a Palm IIIxe would ship for abt $89US. The beauty is that most of the existing OS can be replaced to Linux (i tried it .. it didnt go too well
)
http://www.newswire.ca/releases/July2001/18/c2979.html
Check out:
http://www.linuxdevices.com/
http://www.yopy.com/
http://www.handhelds.org/
Ohh the list is endless .. try a search or go to some sites like slashdot and start from there
oh and let me end with my favorite reason for starting on my "Down with Linus" soapbox :
http://midori.transmeta.com/
Happy reading