If you would like to IM with friends using Google Talk from a Windows Mobile Pocket PC or Smartphone, you might want to take a look at…
It is currently in beta-release and free for testing (the current release expires in October if I recall correctly). I tested on a TyTn Pocket PC Phone Edition running Windows Mobile 6. It worked fine IMing to Google Talk. Since Google Talk is based on the protocol developed for Jabber, it should work fine with Jabber as well as its transport gateway.