Due to a user's bug report we just found out that Audioscrobbler is finally publishing "now playing" information through the webservices. This renders the "ago" joker useless but enables the plugin to do what it was originally meant to do.
The "ago" information will always be wrong when listening to music, though it will be right when stopped. This will be fixed in the next release!
You can download an updated version from http://pidgin-lastfm.naturalnet.de/download/lastfm.pl !