iChat Google Talk - Cannot connect mystery.

Question

Using iChat, I cannot connect to Google jabber server.

1. I have deleted all jabber related keychain entries.

2. I tested my user/pass on the web-based talkgadget to ensure I had the correct info.

3. I can connect to the port via telnet, so there is no firewall issue AFAIK.

4. However, testing with Adium also revealed an inability to connect (at 75% it says "Host unknown). I surmise there is likely a common cause for both programs failing to connect.

What is/are the likely culprit/s and in what order should I attempt resolution?