As you all know, google put a small Google talk box on the gmail page. Nice touch I thought. So now when I check mail, I can also see people online.
Now the problem is when you're logged on to the desktop client too. Then a window pops up in gmail as well as gtalk, but if your friend is using the desktop client and so are you, then only the first message comes up in the Gmail client.
If you thought that was it, I'm just getting started :).
If you start talking to a friend on the Gmail client, then later move to the desktop client, you can't see you're recent messages. And by chance if you're friend is using the Gmail client, all messages keep appearing there. Oh boy!!
And now for the killer. If you're using just the gmail client, you start talking to a friend, but managing multiple chats inside the gmail client is a pain. Imagine having multiple windows as below clouding the bottom part of your Gmail page.

The guys at Google thought of that, and they created this nifty feature of allowing you to pop out a chat window.
So you might have multiple chat windows open at any point of time. But once in a while, you might refresh the gmail page to see if you have any new mail. Or God forbid you close the browser. And poof!, all the chat windows you popped out are gone!!!
Google though gives you this very handy message below!

P.S. I thought I wouldn't post screenshots for the rest of the issues so as not to take the focus away from this gem :).