From EFF:
The new preview version of AOL Instant Messenger raised privacy concerns for us when it was first introduced, first because it started storing more logs of communications and second, because it apparently scanned all private IMs for URLs and pre-fetched any URLs found in them. We met with AOL to discuss how these features work and why the company should take greater care with your data, and we’re happy to say that AOL is promising to make some important changes as a result, especially in response to our second concern.
However, we still recommend that AIM users do not switch to the new version, as it introduces important privacy-unfriendly features. Unfortunately, AOL’s moves are in keeping with a general trend toward more pervasive cloud-based services in which your personal chat data is centrally stored in plain text and an easy target for law enforcement and criminals. This shift toward central logging is troubling in many situations, including in chat.
Read more on EFF.