The Apple iPhone 3G has gone on sale in the UK, as well as in 22 other countries around the world. Pocket-lint headed into the centre of London early this morning to see how the initial demand and sales were going.

Around 100 people were queuing for the device at the flagship Apple retail store on Regent Street in London, while outside the O2 shop similar numbers were in line. Carphone Warehouse also saw healthy demand with folk braving the early morning chill for a place in the queue.

Reports are coming from those who've been in store, or spoken to staff, that queuers could face seriously long waits due in part to the new in-store credit checking and contract admin process.

But, Pocket-lint spoke to some folk who'd been quoted a 4-hour wait time, apparently due in part to software problems with linking the Macs in the Apple store to the Windows-based O2 system.

Meanwhile, thousands who ordered the device online, either via O2's troubled site on Monday or Carphone Warehouse's online shop, will be eagerly waiting at home for the promised couriers to turn up.

Existing iPhone owners will no doubt be busying themselves today with the release of iPhone 2.0, the new firmware for the device, as well as the App Store, that has gone live with over 500 applications for the touchscreen mobile.