I live in Holland, where the PRS-650 was out of stock too. 2 weeks ago they appeared on sale on the Sony site only. When I tried to buy one, the salesperson from Sony they were already sold out: they had 200 pices which were gone in less then 2 hours....
Last week they called teh wer available, and I ordered mine at once. My wife just called there was a parcel, so I think I quit work a bit early today
I think Sony had problems manufactering the device, as now I see the PRS-650 is in stock at Dutch resellers like Bol.com and Dixons.nl, which haven't had it since december!