I wonder if Mobileread might start up a Safari Online forum. Safari Online provides online access to books, quite a lot of technical content out there, and recently added a mobile capability:
http://www.safaribooksonline.com/Corporate/Content/mobile.php
so it is accessible from iPhone or other mobile phones. Apparently some have been able to get this to work from Kindle-2s and various other e-books, to some degree. I have not so far found a Forum up anywhere else, although they have facebook, linkedin, etc. (but those are pretty lame).