Those two programs could be used to remove the FairPlay DRM on iTunes store-purchased MP4 files at zero loss in quality because they were able to capture the decrypted MP4 file in memory and save it. Well apparently the authors of those programs started a new project called Requiem that was a deCSS-like attack on the encryption itself. Apple responded immediately by serving cease and desist letters and updating iTunes to 7.6 and QuickTime to 7.4.1, both of which break all current FairPlay-defeating tools. What's more, the authors of MyFairTunes and QTFairUse (and FFU, another tool) are fully complying with the letter and will not update their programs to defeat the current DRM.
This blows. I updated both iTunes and QuickTime recently, because QTFairUse6 always kept pace with the releases. Well now I'm stuck and can't go back, which sucks because I just bought a track today from the iTunes store.