No problems here
I queued up at 6am in Aylesbury, only to find no queue at the Carphone Warehouse. The O2 shop was closed for refit, and that's probably been for the best. I was in at 8.02 and walked out at 8.15 with 1 (of 2 in total) 16GB iPhone 3G.
No activation required (as far as I am aware, it certainly didnt seem to be done in the shop), just a single signature on a computer printed contract and a simple credit check to content with... Easy peasy?