Not only did Apple update Snow Leopard, but they also issues a security update for both the Leopard Client ("Client" that's what most Mac users have installed) and Leopard Server. Per usual Apple is short on details, but this security update should fix a few holes recently reported. If you are still running Leopard, then Apple advises that you install this update at your earliest opportunity. You can either download it directly from Apple, or you can use Software Update under the Apple Menu. The standard download from the Apple Support website comes in at 240mb for the Client version and 448mb for the Server version.
If you have Snow Leopard installed on your computer, then this update is not for you. Not sure if you have Leopard or Snow Leopard? The easiest way to determine your current version is to click on the Apple Menu and choose "About This Mac." This will load up an information box that shows you your current Mac OS Version as well as some other basic system information.
If you have 10.5, then you have Leopard. If you have 10.6, you have Snow Leopard. To use Snow Leopard you must have an Intel Mac. If it shows you PowerPC, then you must continue running Leopard, if it says Intel then you can purchase Snow Leopard for $29 from Apple.
As you can see from this image, i'm running 10.6.4. I also have an Intel 2.53Ghz Core 2 Duo with 4 GB of system memory. If you click on the "More Info..." button you can learn even more about your system.
About Security Update 2010-007 (Leopard Client)
Security Update 2010-007 is recommended for all users and improves the security of Mac OS X. Previous security updates have been incorporated into this security update.
For information on the security content of this update, please visit this website:http://support.apple.com/kb/HT1222.
SHA 1 digest = 50ff8cb66104cd2a01b66677864619e0fbed4d98
For explanation of what a SHA1 digest is, please visit this website: About SHA1 digest