Adium 1.3.6 is now available. It includes an updated version of libpurple which fixes the vulnerability revealed earlier this week which has the potential to allow another user to run code by sending you a specially crafted message over the MSN protocol plus many Yahoo regressions from 1.3.5, one of those being the problem where Yahoo contacts had signed off still appeared as online.
1.3.6 also features an updated version of the Facebook chat plugin, fixing a number of issues, which were present in Adium 1.3.5 including unwanted email notifications, dropped messages and missing contact icons. It is strongly recommend you update.
Meanwhile, work continues on Adium 1.4, the next major release.