50 Cent has launched a contest encouraging fans to create and share their own remixes of 'Baby By Me,' the single off the rapper's recently-released fourth album, 'Before I Self Destruct.' But, there is a "but." The contest, a joint promo with Vitaminwater, is to be done solely on 50's new iPhone and iPod Touch application, 50's Sound Lab.

The new application gives access to the key elements of the original recording of 'Baby By Me' and provides creative tools that allow anyone to give the new single their own personalized sound. 50 also plans to give fans the chance to show off their skills as part of the contest. When all the remixes have been uploaded, he will pick the best remix of and invite the winner to meet him at a recording studio.

"Musical talent unfolds in many ways and I'd like to see what tomorrow's producers can do with my track, nothing but a bottle of Vitaminwater, my 50' Sound Lab and an iPhone." A free download of 50's Sound Lab App is available from the iTunes App Store.