Google Talk works for me!
Google Talk works! I used these settings for a Jabber account with iChat:
Description: mrbill@gmail.com
Jabber ID: mrbill@gmail.com
Password: mypassword
Server: talk.google.com
Port: 5223
Connect using SSL selected
Allow self-signed certificates selected
Update: Looks like Google Talk has been officially released. They only have a client for Windows right now, but provide instructions on using Jabber-compatible IM clients on other platforms.
August 23rd, 2005 at 8:55 pm
Well, we are already talking there, MrBill! Ttyl

Congrats for the historical login
August 25th, 2005 at 8:08 am
Posted some features and screenshots if anyone is interested, http://nunzi.blogspot.com