After getting a site set up with several users and groups, it seems that the search functionaliy in Share could use some work. Among the issues:
1. Searching with a username does not return any results - (it seems to only search Firstname and Lastname)
2. Searching for yourself produces no results
3. No obvious way to search for *all* users
#2 isn't such a big deal, though I think it's silly to try to catch the special case… #1, however, is a major usability issue, especially for admins who are used to identifying users by username. I think #3 would just be useful all around, especially when building groups.