J.K. Rowling reveals interest in producing an eighth HP book

"Not yet, but "maybe 10 years from now," said J.K. Rowling, after announcing while at the White House's
easter egg roll. She did state that she was up for writing another HP releated book, aside from the
HP encyclopedia she is underway with, which is rumored to be released within a few years.

Could this mean an eighth Harry Potter novel? Or could it be a seperate book altogether?
Perhaps a full-length prequel in addition to the page-long story she already wrote?
J.K. Rowling neither confirmed nor denied these seemingly important peices of information.