If you're a long-time user of Apple’s cloud-based services, and have been using your Apple ID ending in mac.com or me.com to chat over the AIM network, starting June 30, you'll have to be running Mac OS X 10.7.2 or later, reports "MacIssues" (http://tinyurl.com/m26vn4a).
When Apple introduced its .Mac and subsequent .Me cloud-based services, it included cross-compatibility with AOL’s AIM service. This meant that when using iChat, you could log in with your .mac or .me username and be able to connect with AIM users.
Apple says that (http://tinyurl.com/myjkjtk) to "ensure a secure and reliable experience," customers using a mac.com or me.com ID to login to the AIM service via iChat must upgrade their Mac to OS X version 10.7.2 or later by June 30 to continue using the AIM service.
iChat functionality including...| Read more »