I give Mark credit for providing functionality here without a lot of work on his part. I'm sure it's all priorities.
That being said, J_Catlady has a point. Ease in finding groups to join is important to both group owners and potential group members. A lot could be done to improve this interface. Very few people are capable of sussing out url search syntax like Duane. Perhaps we can do Mark a service by figuring out what could be done to make the interface more useful.
The simplest value add that I can see is to use the choice of sort orders on the left (Most Popular, Most Active, Newest, By Name) to sort the results of a search, not just the unfiltered list. I would also change the collation sequence of the By Name sort to be case insensitive. Much more sophisticated Google-search-like approaches are possible, I suppose, but this sounds relatively simple to implement.
Let me repeat: I would give this some priority because it would make gio groups more accessible.