Just to let you know that, despite the fact your claim here:
Works perfectly with WordPress Multisite 3.1
This plug just messes a LOT with WPMU 3.1.
It totally brokes the category links.
- install 3.1
- install the infamous plug
- click on a category link ( /category/something/ )
- Voilà: 404 page.
- deactivate the plug
- go to admin > permalinks
- resubmit same config
- category goodness is back.
This made me lost 5h and a lot of sweat to find out, plug-by-plug / each time resubmitting permalink config to find out that.
Global Site Search plug brings the same issue!