These crazy hackers are moving fast these days, but Engadget has stayed in stride by providing a walk-through of myTunes, a GUI front-end to QTFairUse (sadly, Windows only - for now), that python code they mentioned earlier this week (not to be confused with any other products by the name of 'myTunes').
A big downer for this app, however, is the way it works its DRM-be-gone magic: it can only work on tracks as they're played in real time. Even then, you're left with a file (sans any metadata like ratings or ID3 tags) which needs to be re-constructed into a playable AAC file with a second tool, though that process seems to take mere seconds per track. Engadget recommends letting the stripping process run overnight, so you can get a good 8 hours or so of unshackled music from each batch. Check out their walk-through for more instructions and ideas on how to optimize this process.
myTunes might not be pretty yet, but it sounds like the developer(s) have a polishing roadmap in place, including simplifying this to a one-step process. For now, it still is the only method we know of for setting your iTMS purchases free.