Same thing for me, it worked great after a fresh install, but if you try to update to the new 2.0.2 version with emerge, then pidgin become broken. It's impossible to launch it, via menu and command in terminal.
pidgin is really installed, this is what I get from an emerge -s pidgin:
Latest version available: 2.0.2
Latest version installed: 2.0.2
Size of files: 7,654 kB
and if I try to run it :
bash: pidgin: command not found