you can sign into your AIM account and chat with your AIM buddies right inside Gmail. When you log in to AIM through Gmail chat, your AOL buddies will appear in your chat list with friends from your Google Talk network, and you will see the yellow "running man" logo to the right of your AIM friends' screen names. To your AIM friends it will look like you are logged in to AIM as usual.
Read it from Official Gmail Blog