QuickTime Player X and Snow Leopard
Mac OS X 10.6 Snow Leopard includes a new version of QuickTime, version X.
QuickTime Player X is a front end to this new technology. That player application offers fewer export options than were found in QuickTime 7 Pro.
Specifically, custom installed QuickTime components do not appear in QuickTime Player X. Instead, more generic options appear, to help with exports to devices like an iPod or Apple TV.
Turbo.264 and Turbo.264 HD function by installing QuickTime components, that QuickTime Player X does not offer access to. Therefore, the new QuickTime Player X is not suitable for exporting using Turbo.264 and Turbo.264 HD.
QuickTime Player 7 and Snow Leopard
The default install of Snow Leopard does not include QuickTime Player 7.
Users can select to custom install the older QuickTime Player 7 in addition to QuickTime Player X.
Once you install QuickTime Player 7 under Snow Leopard, you will find the app in the Utilities folder (not the Applications folder) where you can enter a Pro license key and do exports using Turbo.264 and Turbo.264 HD.
Installing QuickTime Player 7 will not affect the underlying QuickTime technology in Snow Leopard - that will still be QuickTime X. You are only using a different front end to QuickTime X, one that offers more export options.
Use QuickTime Player 7 with Pro access when you want to export using Turbo.264 and Turbo.264 HD directly from QuickTime.
Turbo.264 HD hardware and Snow Leopard
Other applications that leverage Turbo.264 HD hardware should work as expected in OS X 10.5 and 10.6 - the same export options you're used to will appear.
You can open the Turbo.264 HD applications, add video to their interface, and select preset or custom options. That will work normally under OS X 10.6, and does not require the installation of QuickTime Player 7.