Expected to ship from the 18th of March (though this in the US and perhaps a bit later here).
US prices: 51" $1,999; 64" $3,499.
Taking the current exchange rate into account and that fact that we generally get shafted in the UK, I'm guestimating prices will start at $1,500-1,600 and £2,600-2,800, respectively. I could be very wrong, of course.
The US market gets a 60", too, so I'm not sure why we're restricted to the two sizes in the UK. If the F8500 comes very close to the ZT65's performance, it represents excellent value, since the 64F8500 would be roughly a grand less than the 60ZT65.
In case you couldn't tell, I'm excited by the prospect of this television!