While Apple's QuickTime focus has shifted to the new QuickTime X technologies, Apple still provides QuickTime 7 as an optional install so people can use features such as authenticated streaming video, QTVR and other interactive QuickTime content in Snow Leopard. Apple today has released a small update for the older QuickTime player.
The update weighs in at 10.65MB and should be available through Software Update; however, it is also available through Apple's support website: http://support.apple.com/kb/DL923
The update requires OS X 10.6.3 or later to install (there is no mention of 10.5 support), and upon inspection of the package contents will just replace components of the QuickTime application itself and does not touch the underlying QuickTime frameworks and libraries. Therefore it appears to be just be a compatibility fix for Snow Leopard.
If you do not have QuickTime 7 installed on Snow Leopard, you can get it by following the instructions in this knowledgebase document. Be sure to update the program after it is installed. If you no longer want QuickTime 7 installed, you can remove it by just dragging the application to the trash (it is in the Utilities folder by default).