The mysterious white iPhone 4, in the wild.

Adding extra legitimacy to credible reports that the white version of the iPhone 4 would arrive within the next few weeks, the unit has already popped up at a Vodafone UK retail store, and has even been sold to a customer before stock was pulled.

Engadget has a photo from a reader who claims to have purchased the 16GB model of the yet-unreleased device from a Vodafone store in the U.K. Following the sale, the carrier is said to have sent a message to stores telling them to hold the stock until next week.

The white version of the iPhone 4 was supposed to launch alongside the black one in 2010, but manufacturing difficulties have pushed its release back nearly a year. Following the original iPhone, the iPhone 3G and 3GS were both available in black and white, though with the iPhone 4, Apple radically changed the manufacturing process and added color to the front of the device as well as the back.

According to Engadget, the model number on the white iPhone 4 the customer purchased (MC604B/A) is only slightly different than that on the currently available black version (MC603B/A). This suggests that any major differences between the two phones, other than color, are unlikely.

Reports emerged last week that Apple planned to get the long-delayed white iPhone in stores by the end of the month. Apple later confirmed it was nearing its targeted launch timeline of "spring."