I just looked at the Ebook section of the Fnac website. While the selection seems still poor, the principle makes a lot of sense.
They works with the Cyberlibris company, and the website works as a librairy, with a price of 6€/month for access to all the books and a starting price of only 1.49€/month for only one "category" of book.
(You can suscribe only to one or to a few category of book, which would be great for me as I read a lot of history books. Strangly, there is no fiction category for the moment.)
The only problem is that the service only allows you to make a paper copy. You can print the document on paper, but you cannot backup it in electronic form
PDF Printer are not authorized. When you cancel the service, you lose all the books you have not printed.
Also, the books seems only available in PDF for the moment.
I hope they will seriously beef up their offer for the PRS-505 release, while keeping the same functionment and price tag.
I will certainly try the service as the first month is only 1€ for one category of book, and there is no lenght commitment.