I use both Pidgin and Adium for chat clients. Both use libpurple, which has always been a good thing... that is until 2-19-2009. Why does that day live in infamy, you ask? Well that is when Adium updated to a new version and broke my gTalk network.
The symptoms are kind of strange. I can connect Adium to gTalk and my contacts load and turn grey. When I right-click on a contact, I get an option to 'Re-request Authorization', almost like I was blocked by all 200 gTalk contacts at once. I'm one for conspiracy, but I am also one to believe in software problems. Especially when I can use the Gmail interface to talk to my gTalk clients with no problems at all. I'm fairly sure it is libpurple because that seems to be the only link between Pidgin (on windows) and Adium (on mac) and they both broke at the same time.
So, libpurple developers out there, please look upon me with grace and kindness. Fix your freaking software and let me gTalk it up once again!