A new cairo has been uploaded to Debian this week which means than the new GTK 2.7/pango 1.9 can be built now. I’ve uploaded packages of the current version to Debian experimental.
Note than firefox has some issues because gecko assumes than gtk uses pangoxft which is not true with cairo, you can workaround it by editing /usr/bin/firefox and not exporting MOZ_ENABLE_PANGO.
(you can use “deb http://people.ubuntu.com/~seb128/gtk ./” for Ubuntu packages)