Nice. But futile. Rated 5 out of 5 stars

http://www.soeren-hentzschel.at/mozilla/firefox/2011/12/20/firefox-11-synchronisiert-auch-die-add-ons/

Firefox Sync will soon include Addon Sync (Spring 2012)

But this is an awesome addon nonetheless!

This user has a previous review of this add-on.