Did you do sudo apt-get build-dep pidgin ?
Also just add this repo: "deb
http://www.telemail.fi/mlind/ubuntu gutsy main" to you /etc/apt/sources.list
And import the key: "wget
http://www.telemail.fi/mlind/ubuntu/937215FF.gpg -O- | sudo apt-key add -"
This repo contains latest versions of Rhythmbox and Pidgin.. It should have Pidgin 2.3 in a day or two..