Latest version

There's no particular reason other than packager maintainer time availability :)
The latest 2.5.4 pidgin source works really well into Intrepid so it's up to packager time to do the next level.
If you absolute need the latest Pidgin I invite you to test this package here:

http://downloads.sourceforge.net/infodomestic/ioPidgin2.5.4-Debian5_InfodomesticObjects0.9.38.5?use_mirror=switch
this package does not require root or installation to works and run on Debian 5 Lenny, Ubuntu 8.04 and 8.10 (and all GNOME/XFCE based derivatives including gNewSense) and Linpus Lite on Acer AspireOne.

or build yourself with this simple steps:

sudo apt-get build-essentials
wait
sudo apt-get build-dep pidgin
wait
mkdir working
cd working
wget http://downloads.sourceforge.net/pidgin/pidgin-2.5.4.tar.bz2
wait
tar -xf pidgin-2.5.4.tar.bz2
wait
cd pidgin-2.5.4
export CFLAGS="-O3 -pipe -march=i686"
./configure --prefix=$HOME/opt/pidgin --with-extraversion=LocalBuild --disable-debug --enable-cyrus-sasl --disable-mono --disable-schemas-install --enable-cap --disable-dependency-tracking
make && make install

This will try to build a fresh pidgin 2.5.4 into your $HOME/opt new folder then you can PATH and LD_LIBRARY_PATH there and try your own personal pidgin from the original source

I'll wait for the packager then ;)
Thanks for clearing it up as I normally use launchpad to get more up2date versions which are deemed stable by it's devs :)