Google announced this program awhile ago, though obviously are now releasing some additional details.
I'm not sure how many publishers will be on board with providing new books to this program, though. Right now the wholesale cost for a new ebook is around $10; if Google sells (leases?

) a new ebook at $15.00, the wholesale cost will drop to $6.75. This is exactly the type of price reduction many publishers are trying to avoid.
I'm not too concerned about the "Cloud" aspects, although from a technical perspective I'm not sure how well it will integrate (if at all) with their existing partnerships with Sony and B&N, how it will work with an Internet-connected ebook reader, or if it will require additional software.