talk.google.com on the right hand side
it can also be downloaded with other Google Programs in Google Pack - HERE
And Google Pack will keep everything that you download updated.
any faculty member that you add will Auto-accept your "invite"
You can also Call and "talk" like you would with a phone to someone on Google Talk.
Google Talk Will Also Notify you of Email's as they arrive, so you can keep your browser closed if you wish...