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 About the Mac OS X 10.6.2 Update page for a list of changes. Also note the page detailing the security improvements in this update.

A few important items do jump out:

• The update fixes the Guest account deletion bug that would delete one's own user directory when you logged back in after a Guest login session was complete (see "Apple Acknowledges Guest Account Data Loss Bug, 13 October 2009).
• You can now open multiple downloaded files via the Finder reliably, a problem we covered in "Snow Leopard Bug Prevents Opening Groups of Files," 3 November 2009.
• Apple's discussion forums have been active recently with reports of video playback and performance issues on the latest iMacs released a few weeks ago (21.5-inch and 27-inch models), which apparently is tied to having AirPort turned on; the update addresses it.
• The problem recognizing two-line URLs in Preview has changed somewhat, so although some two-line URLs are recognized correctly, many others are not (see "Two-Line URLs Broken in Snow Leopard's Preview," 1 September 2009). From our perspective, this bug remains outstanding.
• Apple notes "Safari plug-in reliability," which we take to mean "handles Flash better" since the company has identified Flash items as the leading cause of crashes in Safari.

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 "Fix Snow Leopard's Screen Sharing Black Screen Bug," 4 November 2009.)

On the downside, Snow Leopard's bug affecting Apple Events (which Matt Neuburg identified in "Tracking Down Snow Leopard's Apple Events Bug," 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 Mac OS X 10.6.2 Update is 473 MB and the Mac OS X 10.6.2 Update (Combo) 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 Security Update 2009-006 Client (143 MB) and Security Update 2009-006 Server (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 About the Mac OS X Server 10.6.2 Update page for more details. The delta update from Mac OS X 10.6.1 weighs in at 496 MB; the Combo update 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.]