New Harry Potter book?

Maybe, but if so it will be a prequel book featuring Harry's father James (or perhaps a sequel featuring Harry's son, also named James Potter).

James Potter and the Hall of Elders' Crossing

WB say they know about it but won't say if it is their site. It is though very sleek and reminds me of JKR's website.

ETA: Is it a hoax, a fan-novel, or something else? Whatever it is it isn't a eight book.