At best, the patch could hit today along with another database reset, but should be released by the end of this week according to lead producer Chris Sigaty.
The editor will not allow users to publish creations to the Battle.net 2.0 cloud, which is planned for the retail release of the game, but it will give players an opportunity to learn the scripting engine and get to work on their creations. Eventually (a year after release) map-makers will be able to sell their creations on the Battle.net Marketplace.
Additionally, the Mac beta client will be made available 3-4 days following the patch.
As for balance changes in the patch, I'm told that Marauders will be buffed a bit following the "over-nerf" they received in Patch 8, according to lead designer Dustin Browder. This will most likely be tied to decreasing the cost and build-time of the concussive shells upgrade.
Mac Beta! Yay!