Okay, a few more changes:
Thanks to Jayk, I found that the Froogle urls were not being constructed properly. I've corrected the issue in SVN (waiting for confirmation from Jayk that it exports correctly this time).
If anyone wants the updated files:
http://x-cart-seo.googlecode.com/svn/trunk/ <-- go here
The outputfilter and the install documentation were changed for Froogle SEO functionality to work.
I likely won't be able to make any more updates until Monday, everyone have a good weekend.