ok try this then...
go HERE and update slapt-get and update slapt-get to the newest version....
then goto /etc/slapt-get/ and edit your slapt-get.rc files sources to these
SOURCE=http://linuxpackages.inode.at/Slackware-12.0/
SOURCE=ftp://slackware.cs.utah.edu/pub/slackware/slackware-12.0/
SOURCE=ftp://ftp.slackware.com/pub/slackware/slackware-current/
SOURCE=http://darkstar.ist.utl.pt/slackware/addon/slacky/slackware-12.0/
SOURCE=http://software.jaos.org/slackpacks/12.0/
and save the changes that you've made....
go back to gslapt and try searching for pidgin again you should have it now
if you have some problems opening gslapt after updating enter this command at the prompt
slapt-get --search gslapt and it will show all versions available you want version gslapt-0.3.19-i486-1as
so download it by slapt get install-- gslapt-0.3.19-i486-1as and you can use gslapt or if you dont want to use GSlapt and get straight to pidgin do
slapt-get --install pidgin-2.3.1-i486-2McD