There are two known issues of Pidgin 2.6.x, which are related to YuLastfm.
1. YuLastfm crashes Pidgin 2.6.x
This bug is caused by Pidgin or libgtk2-perl modul.
Every time when you using/requiring Gtk2 module in Perl plugins, it crashes.
Since I can do nothing to fix this,
I just submitted a ticket on Pidgin Trac system.
Ticket number is 8499
Go http://developer.pidgin.im/ticket/8499 for more information.
2. XMLNode API Changed
Some users may have found that YuLastfm stop updating tune information since
they updated to Pidgin 2.6.x
This problem is because of part of XMLNode API changed.
Try to correct this by replacing all
Purple::XMLNode->from_str( $_, lenghof($_))
Due to the previous two reasons. I released YuLastfm 0.2.1
This release is dedicated for Pidgin 2.6.x.
However, it doesn't support Gtk2 widget related features.
If you still want to use it, please stay in Pidgin 2.5.x. or wait until Pidgin or libperl-gtk2 developing group fix the problem.