Bloggers complaining about how horrible people are trying to spread around spoilers.
News stories about how there are spoilers EVERYWHERE on the internet.
Other bloggers making up their own spoilers without having read the book.
Still other bloggers making fun of the people who feel like they have to take "Harry Potter Day" off and hide in a cave and read the whole book reallyreallyfast.
So in the end, I think that even if you live on the internet (as I do), you'll probably be safe. Unless you were in Dallas when this guy drove by the bookstore and yelled out the ending. (Mind you, I have no idea if it's true, and I can't even remember who Dumbledore is, but the "Noooooo!" one girl yelled out was funny.)