According to reports starting to leak out from reliable sources, a new 3G version of the iPhone may be launched Monday in the UK in a joint promotion with Vodafone, T-Mobile, and UK phone retailer Carphone Warehouse as an MVNO.

A report in the London Evening Standard newspaper (no link available) yesterday hinted that Vodafone would be the official carrier in Europe, but Newswireless (run by long-time mobile journalist Guy Kewney) today says Apple is going with three carriers in Europe to answer criticisms folllowing its exclusive deal with AT&Tin the US. The announcement is slated for Monday but an actual shipment date for the 3G iPhone is unknown, although it is looking like the year-end.

Vodafone recently launched flat-rate data charges for its under-used 3G network, making it a good platform for the iPhone, while T-Mobile has positioned itself for a while as a flat-rate “Web and Walk” carrier. Carphone Warehouse, though a left-field choice, is said to be in the frame as a MVNO carrier in the UK. The American version, using only 2G phone technology, goes on sale in the US today.