Since AIM users are now able to send messages to Google contacts and vice versa regardless of which client the person is using, it will open up a whole new avenue for you to keep in touch, never mind if it is using AIM via Google Talk, Gmail, iGoogle, Orkut or any other Gtalk client. Gmail users are able to check out a prompt that asks them to add their AIM buddies straight to Gtalk without any hassle, and users are required to add @aol.com to the end of the AIM contact which they are trying to add for it to run fine and dandy. For example, screenname@aol.com.
Since users are able to add AIM contacts straight through Gmail, Google decided it would be for the better that the ability to sign in via AIM is removed. AOL has also done their part to create a tool to help them quickly add their AIM buddies to Gmail.