Is there a gmail users contact list for google talk?

[Negoish]

Dear Gmail Users,

Have just set-up google talk.

Can you talk to other contacts in gmail network through google talk?

Negoish

[RussellM]

Yes, you can. As you email people in gmail they will be automatically
added to your talk contact list in the gmail application and also in
GTalk.

See this help page:
https://mail.google.com/support/bin/topic.py?topic=12870