I had to deactivate the plugin because it was in conflict with Joomlart's Mega menu. I don't know however if it's safe to uninstall.
--Nibinaear 09:29, 8 September 2011 (CDT)
I have issues when using:
System - Mootools Upgrade System - jQuery++ Integrator by tushev.org
With Showplus / Sigplus and mod_twitterfeed. The mootools upgrade didn't seem to have any effect on the problem which causes a blank screen to appear in Joomla site.