I just noticed that mobilefun dot co dot uk have Sim Free Nokia N9 16GB - Black at £519.95 (inc. VAT), 'In stock' as viewed at 13:30 today. Another seller to add to the list - which should now be increasing...
Hopefully somebody will sell the 64GB variant sometime soon. After the luxury of 40GB with the N900, going back down will be a chore for the 16GB device