Well I just popped into the Hayes (west London) branch. They didn't have any Pre 3s (or a demo phone for that matter) so I asked the guy about release date.
He gave me a knowing smile and said 'I'm not allowed to tell you exactly but some time in the next two weeks', or words to that effect. I reckon the implication being that he knew exactly the release date, but couldn't say when. My reading of 'in the next couple of weeks' is 'not this week, more like sometime next week' (why say two otherwise?).
The guy actually didn't like WebOS (a self confessed Android fan) and wasn't enthusiastic about the pre 3 itself (although he had only handled a prototype - presumably a while back, not recently), pointing out that his impressions on build quality didn't correspond to the 'HP hype'.
Anyhoo, I'll still buy one, no doubt!
Hope that sheds a bit more light on it... but probably not. I reckon we'll all have to spend another week at least twidding thumbs.