TUAW reader Dustin Johnston tipped us off that a new OS X framework is getting installed with the OS X 10.4.10 update, namely Yahoo Sync. Located in /System/Library/PrivateFrameworks, YahooSync.framework contains an embedded Yahoo!Sync application.

If you want to find it on your computer, choose Go -> Go To Folder in Finder and enter:

/System/Library/PrivateFrameworks/
YahooSync.framework/Versions/A/Resources

Peeking inside the application and framework strings reveals that the synchronization will use a Yahoo! ID stored in Address Book and that you must (obviously) have a Yahoo! account set up in order to synchronize. It's not clear exactly what this application does, but it's likely to allow you to sync your Yahoo! calendar with iCal.