I've been using Trillian for some time now so that I can use multiple IM services with one client. Well, I recently have been getting disconnected from AIM with the message that I am using an unsupported client with their service. At first I thought that I just logged in incorrectly, but every two minutes or so I would get disconnected with the same message. I went to Trillian's website, which said that the developers were aware of the problem and are working on a solution. This is what's great about the hacker community (I'm not talking to you punk kids who think you're hackers). They see a problem and they work on a solution. However, AOL will probably see the solution as a problem, and come up with their own solution, and thus a cycle of updates will occur, and eventually neither side will win, because nobody will want to use a crappy service that constantly needs updating.
The only reason I can think of for AOL to block unwanted clients is because of the advertising possibilities with their own client. I would hope that AOL would have enough cash to run an IM service, but I guess not. Maybe we'll all just go back to the old-fashioned way of interpersonal communication: e-mail.