Apple has updated a few knowledge base articles that address problems with the Aperture 3 update, disc-burning issues with iDVD, reinstalling the Server Diagnostics utilities on the Mac Mini server, and managing noises in newer iMac models.
This article covers a problem with the upgrade to Aperture 3, where the program will unexpectedly quit after you have upgraded, either after or during the point where you enter your serial number. The fix involves removing a file from the shared Application Support folder for Apple's "Pro" applications, and then re-entering the key.
This article provides a variety of reasons why iDVD will not burn to a DVD, and covers small tips on what to do for each scenario. Even if you do not use iDVD but are experiencing burning problems, the tips and suggestions in this article may be useful.
To reinstall Apple's diagnostic utilities, you will need to reinstall the operating system off the discs that came with the computer. This is also the case with the client version of the OS; however, unlike the client version, Apple has the server diagnostics available as a separate download (I wish they'd provide this for the client versions as well).
Apple has a small article covering noises you may encounter in late model iMacs. Yesterday I wrote an article covering similar, but this one covers hard drive, CD/DVD drive, and fan noises you may hear from late 2009 model iMacs.