Cool! Native support for geospacial types and queries would be awesome. Geohashes are on the roadmap. If you would like to get more focus on it, make sure to vote up the feature request, and update that topic with your use case.
Note that even though SQL made that look easy, I think we can be pretty confident that query took a full table scan to complete. Even though it limits to 20 rows, it still had to calculate everything to order it. You can do the same thing with Fauna – it just won’t scale well. Then again, neither will that SQL query.