People familiar with the matter say the forthcoming builds are likely to be released to some developers in the next 48 hours, and carry the expected prefix of 10Dxx. It is not yet known what issues Apple hopes to address with the latest update.
A month ago, Apple released Mac OS X 10.6.2, which corrected a guest account bug that could potentially delete a user's account data, triggered by logging in and out of a guest account on a Snow Leopard machine. The update also included native support for the Mac maker's new multi-touch Magic Mouse.
That update was in beta for just over a month, before its release to the public on Nov. 9. A timeframe for the potential Mac OS X 10.6.3 release is not yet known.
Updates for Snow Leopard thus far have come quickly. The new operating system, released at the end of August, saw the 10.6.1 update arrive less than two weeks later. The next build took about two months before it was released.