Minor update to the Retina MacBook Pro expected this week.
Apple Begins Seeding Mac OS X 10.6.3 Build 10D522 to Testers
Apple documents four remaining known issues in the current build, related to application updating, Displays preferences, iTunes hangs, and ColorSync Utility Filters.
Word surfaced nearly a month ago that a 10.6.3 beta release was imminent, but Apple apparently decided not to push any testing versions to developers until after the holidays. Apple's last update to Snow Leopard, Mac OS X 10.6.2, was released nearly two months ago.