I don't know about you, but I'm not sure I trust any British folks at the White House given how they burned the place down back in 1814, so make sure Secret Service keeps their eyes on the author.
If you can't get to the South Lawn (kids have to be under 12 years old to participate in The Roll, and have to be better connected than I am), Ms. Rowling will be reading portions of Harry Potter and the Sorcerer's Stone live from 1:30 - 2ish PM on WhiteHouse.gov.
Does anyone have a child under 12 years old I can rent for the afternoon this Monday?