Apple has released Mac OS X 10.6.2, a sizable update to Snow Leopard that touches on many areas of the operating system. The changes are too numerous to chronicle: read Apple's page for a list of changes. Also note the  in this update.
A few important items do jump out:
While Apple didn't note whether or not it fixed the problem with Snow Leopard screen sharing - in which remote screens appear all black until the quality setting (View menu) is toggled or reselected - we no longer have the problem when connecting from Snow Leopard systems running 10.6.2 to other computers. (See "," 4 November 2009.)
On the downside, Snow Leopard's bug affecting Apple Events (which Matt Neuburg identified in "," 13 October 2009) is still present. Also, Mac OS X 10.6.2's screen saver seems to take a very long time to build a list of files to display when pointed at a folder or folder hierarchy containing more than a few thousand images. This stands in stark contrast to numerous previous versions of Mac OS X.
Mac OS X 10.6.2 is available via Software Update or as two standalone downloads: the is 473 MB and the  is 479 MB. Typically, the Combo update would update Mac OS X 10.6.0 and higher, while the regular update would cover only Mac OS X 10.6.1. Presumably, the small size difference is related to the fact that Mac OS X 10.6.1 was an extremely small update.
Also, the size of the update via Software Update can vary widely, depending on your computer. My 2.33 GHz MacBook Pro, released in 2006, required a 499.9 MB download, while my Mac mini from earlier this year needed a 157.7 MB download as was a colleague's Mac Pro from early 2008.
Apple also released (143 MB) and  (231 MB) for Mac OS X 10.5.8, which include the numerous security enhancements in Mac OS X 10.6.2, linked above. As ever, the issues addressed patch vulnerabilities exploited by maliciously crafted files or Web sites.
Snow Leopard Server also receives numerous fixes for problems synchronizing Portable Home Directory content, using the iCal Web interface within certain time zones, creating images with the System Image Utility, server-side filtering of incoming mail messages, preventing brute force password attacks, and more. See Apple's page for more details. The  from Mac OS X 10.6.1 weighs in at 496 MB; the  is 503 MB.
[Note: This article was updated after publication to indicate that we have found the Snow Leopard screen-sharing bug appears to have been eliminated.]