i installed it on my n900 but it didnt work, even after changing the MCE LED Pattern from 'PatternCommunicationChat' (doesnt exist in maemo 5) to 'PatternCommunicationIM' or any other one in mce.ini.

UPDATE:
apparently it does work! i dont know why it wasnt instant, but it works fine now.

steps:
1) download: http://maemo.jabber.dk/pidgin-n800-l....2-2_armel.deb
2) in xterm as root, go to the directory you downloaded the file to and install it with: dpkg -i pidgin-n800-led-plugin_0.2-2_armel.deb
3) start pidgin and go to TOOLS->PLUGINS. find the "Nokia LED Plugin 0.2" in the list and click Configure Plugin.
4) where it allows you to enter an MCE LED pattern to use, enter:
PatternCommunicationIM
close out of it all and see how it works. it took about 5min for it to begin working for me -im not positive what caused the delay.
might need to restart the mce service to reload mce.ini if you want instant gratification.

enjoy, and thanks to the guy who made the plugin to begin with!