Reprinted without permission:
Although you or the owner of the Content retain ownership of all right, title and interest in Content that you post to any AIM Product, AOL owns all right, title and interest in any compilation, collective work or other derivative work created by AOL using or incorporating this Content. In addition, by posting Content on an AIM Product, you grant AOL, its parent, affiliates, subsidiaries, assigns, agents and licensees the irrevocable, perpetual, worldwide right to reproduce, display, perform, distribute, adapt and promote this Content in any medium. You waive any right to privacy. You waive any right to inspect or approve uses of the Content or to be compensated for any such uses. [Emphasis added.]
Content You May Use
AOL, its vendors and AIM users who lawfully post content such as information, software, games, communications, photos, video, graphics, music, sound and other materials ("Content") on AIM Products own the property rights to that Content. ...
This means that anything you say or transmit over the AIM protocol -- whether using the AOL Instant Messenger client, Trillian, GAIM, or any other client which uses the AIM protocol -- can be used by AOL and its affiliates (etc.) in any way they wish, without any right to privacy, or any say in how this "Content" is used.
If you cherish your privacy, or your right to your own intellectual property, then be cautious before posting anything (private conversations or personal property) over the AIM client, or the AIM service using other clients (such as Trillian or GAIM).
I'm personally thinking of not using AIM any more.. and switching to other services. (Note that ICQ and other services are owned by AOL.)