A few years ago, a fellow named Jon Johansen (aka, DVD Jon) exploded onto the scene with some really cool technology: he released DeCSS as a means to “liberate” DVD films from onerous copy protection.  I don’t want to go through the legal and moral arguments that his actions provoked.  But later, he became more legit when he helped to form DoubleTwist.
When DoubleTwist first hit the market, it was a means of decrypting iTunes music files for use by other applications on your PC.  This meant that it was a very speculative venture.  First, it was taking aim at folks who were ostensibly “protecting” musicians and their copyrighted works.  Second, the folks who needed decrypted versions of music (on their desktops) were a limited community: most of them were using songs that they had purchased as input to other programs (e.g., DVD authoring tools, etc).  So while I tried the product, I decided to buy music from Amazon instead.  So until recently, DoubleTwist was cool – but not very useful for me.
But Jon & Co. have finally pulled together a more expansive reason for DoubleTwist: syncing media with Android devices.  DoubleTwist is now a free product that can sync any (or all) of your iTunes files with your Android device.  The product is free to use.  So DoubleTwist is making its money in a different way – it is now a distribution channel and an advertising platform.  For those that have an Android device, you can buy apps from within DoubleTwist.  And you can also buy music and movies from Amazon through the DoubleTwist tool.
So the way that you can legitimize a hacking tool (that decrypts protected media) is to become a media intermediary.  I am sure that DoubleTwist is giving the media “market” owners a “cut” of their business.  That way, a previously offensive technology is now legitimized.
But is it a good tool?  After a few hours of playing with the tool, I am thrilled to have a free tool like this.  Yes, you can buy tools to sync with Android phones.  But I am happy to recommend this tool.  It syncs the music I want to sync.  It scrobbles to Last.fm.  It allows you to set songs as ringtones.  It also downloads and displays album art with ease.  After a few more weeks, I may revise and extend the recommendation.  But for now, I give DoubleTwist a qualified “thumbs up” on the Roo-meter.
-Roo