Configuring Pidgin for Gtalk on Ubuntu

Default settings may not work for you like they did not for me. Here is what worked for me:
Once you have setup your account change the following settings on
accounts->abc@gmail.com->edit account
Basic->Protocol set to XMPP
Advanced->Connect port to 443
Advanced->Talk Port to talk.google.com
Advanced->Connection Security to old-style SSL

You might also want to go to
Tools->Plugins->Libnotify Popups ->Configure Plugin-> Uncheck Buddy signs on, to disable annoying notifications every time somebuddy comes online.