CrashPlan has documented this information in their support wiki.
http://support.crashplan.com/doku.php/how_to/configure_a_headless_client
I know everyone is loving the new Asus Eee PC and they should, its a wonderful device. But if you want to go even smaller you can take a look at Aleutia E1 it only takes 8 watts of power and can be charged using solar power. Definitely for the out and out and about type traveler that needs a small computer that can be charged easily, combined with a sattlite phone for data and you have all that you need in a remote location.
MobileChat supports the following protocols: * AIM/ICQ/.Mac/MobileME * Windows Live/MSN * Yahoo Messenger * GTalk * Jabber/XMPP Multiple Accounts