Arrived outside O2 in the UK at 8am to a queue of about 10 people. By 8.45 there were another 5 behind me. There is a CPW directly opposite who opened their doors earlier than O2. All those behind me, and me, went over to CPW - the first guy left without a phone as they were not doing PAYG, only contract. I bought a black and a white 16Gb (one for me, one for my wife - I have a 3G but am putting the SIM in that into the 3GS and giving my 3G to my daughter to get around the contract!). I walked out with the first two 3GS sold in Hertford! One other person bought one at CPW after me, everybody else in the O2 queue was buying a PAYG.
I didn't expect huge queues today because of the contract shenanigans, and there weren't any. Not sure what the UK Apple Stores would be like though, as opposed to the O2 / CPW stores.
Haven't unboxed it yet.