Category works with Organic Groups
Since I'd seen that some people were unsure whether Organic Groups and Category are compatible, I thought you'd all be pleased to know that I'm testing them together, and so far they're playing quite nicely together.
I've done the testing on a couple of non-production installations over at http://www.bookmuncher.com/. I'm doing some restructuring to my production site, but I'll have the combination of the two live soon.
Works for me
I just tried testing OG with the taxonomy wrapperi, and was having no problems. If you're still having difficulties, please post a description of the problem as a category module bug report on drupal.org.
Taxonomy Wrapper, breaks OG
OOPS!
Although they were playing well together at first, once I dropped in the Taxonomy Wrapper, I could no longer make groups. Since I don't think I'm going to be needing Taxonomy Wrapper, I just switched back to the regular file, but I'm sure others will run into this issue.