It sounds very strange to me, I must have lost it, but it seems like nobody has written about Gtalk in Gmail, yet.
A few weeks ago I was in a VERY restricted LAN and could only use services on ports 80 and 443.
I went on my gmail account to check for emails using Firefox 1.5 and noticed the “Quick Contacts” frame. I expanded it and noticed that some of my contacts where actually online.
Things to note.
In the “Quick contacts” you can see users’ status, away messages and so on.
When you start a new chat, windows are stacked horizontally, from right to left. I actually haven’t tried to open enough chats to see what happens when the row is filled.
Windows can be opened, minimized or open as a pop-up with the Pop-out feature.
Window titles are highlighted when you have a new message.
The chat is really fast, feels a lot like IRC and not like a slow, clunky web chat with reloads and so on.
Smiles have a nice animation, you see the tag such as “:)” and then it animated and mutated into the smile (as you can see it in the screenshot).
Considering that it’s a web interface, the usability is very high and chatting is pleasant. Refreshes are smooth and you don’t really notice it.
The only thing is that you need to keep the gmail window open. Even if you “pop it out”, if you close the main window, even the other windows will be closed. Luckily you get notified and if you try to close the gmail window you will at least know it.
When you close the gmail window you become offline automatically.