The secret sauce of the latest Michael Robertson foray into the realm of MP3 audio is officially live. Launched in the wee hours of the morning, MP3tunes offers a catalog of 300,000 192Kbps MP3s with no DRM. Pricing per track is a modest $0.88. Beyond higher bit rate files and no DRM, the most compelling feature of the service is a “music locker” designed to store purchases for later download. Most of the current music services allow you to download files once, relying on the purchaser to burn a backup of the files or store them in a way they can be used on multiple machines. Under the traditional model, if a listener’s drive crashes or they accidentally delete a file, it’s gone. The music locker guarantees accessibility to purchased content anywhere you have an Internet connection capable of authenticating with the MP3tunes service. MP3tunes has a tough road ahead if it wants to do a serious transaction volume. The current version of the service lacks any support from major label artists capable of creating demand for offerings in the service. MP3tunes appears to be at the mercy of the indie labels listing tracks with the service to drive transaction traffic because no marketing mechanism currently exists to bring attention to the artists and provide a compelling reason to buy. Bottom line, MP3tunes is a smart business model with some great songs, but knowing what you want to listen to is currently a challenge for anyone not in tune with the scene in any particular genre of indie music. Hopefully we’ll see streaming radio programming tied to the service, or a partnership with some music podcasters capable of recommending tracks to buyers who may not know their next favorite song is a mouse click away.