Pidgin users with Yahoo accounts noticed that Pidgin wasn't able to log in anymore. There was an IP hack that worked for a few days, but Yahoo seem to have nixed that.
Copied from a comment on my card:
The fix [for Ubuntu users] is to install pidgin from GetDeb, at least until the Ubuntu repository catches up. Version 2.5.7 works, and the cause was Yahoo! killing off support for YIM versions 6.0 through 7.5.
