This is about installing pidgin 2.7.9_0 from MacPorts to Snow Leopard on May 7th 2011:

• Install MacPorts (I've been using 1.8.0-10.6)
• Install from MacPorts:
  • autoconf
  • automake
• Make sure, the Macports binary dir is in your $PATH, so autoconf and automake from Macports will be used.
• Install Pidgin with support for Quartz:

PATH=/opt/local/bin:$PATH /opt/local/bin/port install pidgin +quartz +no_x11 

It will run into errors as some diff files do not fit any more. You can remove all patch related entries from /opt/local/var/macports/sources/rsync.macports.org/release/ports/net/pidgin/Portfile and rerun the install command.

• A slightly outdated but more verbose post in the "Lumber Room" did help me a lot, especially the part on “native GTK”.
• There is a binary on sourceforge which is a little bit outdated [as of May 2011], but installs and starts fine.