Not really mobile but at least digital and interesting in any event: a news release has it that Apple‘s iTunes had overtaken mighty Wal-Mart as the US’ largest retailer of music. Best Buy was ranked third and Amazon.com and Target tied for the fourth spot in January and February, it is reported.

iTunes apparently sold more than 4 billion tracks since its launch in 2003. The survey counted every 12 digital downloads as one CD but excluded mobile music sales. Apple claims more than 50 million customers. This is a rather impressive development: They sold around 25m tracks in 2003, surpassed the 1bn mark only 3 years later and hit 3bn in July2007.