I want to thank SpotON3D for sharing their region counts, and InWorldz for sharing their active user numbers.
For commercial grids in particular, growing land area is a sign of the health of the business.
And traffic numbers are very useful for folks and businesses looking to grids to check out. And while many would gravitate towards the busiest grid, some people are also looking for new, smaller markets to explore, or a more personal, cozier grid for socializing. The traffic numbers can show which grids are gaining active users, etc...
Meanwhile, here are some extra stats:
Total number of regions on the 156 grids that release these numbers: 25,545
Total number of registered users: 265,015 (down a bit since last month because ReactionGrid's gone)
Total number of active users: 18,316
Total number of active users on hypergrid-enabled grids: 6,859.
(This includes only the grids I definitely know are hypergrid enabled -- I haven't checked all of them, and doesn't include many hypergrid-enabled personal and school grids that aren't in our directly, such as the Georgia school district's grid. But then again, some of the smaller grids count hypergrid visitors as part of their active users total.)
So there are more users on the hypergrid right now than on any individual commercial grid. And with hypergrid-enabled friends, instant messages, groups, and landmarks its getting easier and easier to reach these folks. Of course, commercial grids have a marketing advantage in that they can send out messages to all of their users, or put up announcements on their login screens. There is currently no way to simultaneously reach all users of the hypergrid, and probably will never be -- it's like trying to reach all the users of the Internet.
So, for merchants, being on a commercial grid gives them the opportunity to buy ads that reach all the members of that grid. (Kind of like buying ads on Facebook.)