The Shelfari content model is pretty simple: Users of the "interactive social media site for book lovers" set up a homepage listing their favorite titles, with links to their reviews, and then they can browse around and see who else loves those stories, what other books those people recommend, what their friends are reading, stuff like that. This morning, the company announced that the completion of its Series A financing with significant investment from Amazon.com, among other investors. "In a short period of time, Shelfari has succeeded in building a vibrant community around the experience of reading, and we are pleased to support them in their efforts," said Amazon books VP Greg Greeley. The online retailer has also put the director of its books and magazine store, Stefan Pepe, on the Shelfari board of directors. Where they're headed with this seems pretty straightforward; the only question is how long it'll take to establish feasibility and incorporate the features into Amazon's site...