Didn't see this posted around here yet, despite it seems that everyone and their moms are from the US around here, I suppose some UK peeps lurk the forums too :D
Excellent - if they follow the sales pattern of other Windows phone devices, they will be sub-£300 pretty quick - about the right time for me to replace my 800!
I'm guessing about $500 off contract in the US based on this. The direct conversion is $560ish, but phones usually cost a maximum of 89% of direct conversion GBP to USD, due to the UK price including tax.