Oversoul - I dislike book burnings as well, but I'm concerned that the president's comments are "they have a legal right, but it is insensitive to others" with the book burnings, but when it talking about the mosque at ground zero, the comments are only "they have a legal right," with not comment about it being potentially insensitive.
My problem with book-burning has nothing to do with it being offensive or insensitive toward those that hold the book being burned in high regard or believe it was originally dictated by the creator of the universe or whatever. My problem with book-burning is that it's book-burning. Maybe the parties doing it think of it as being a form of protest akin to burning a flag or similar symbol, but even if they do (which in most cases I doubt), that's no excuse.
That's not to say that I'm endorsing flag-burning, but it is, at its core, an act of malice for what the flag stands for. Burning a flag takes the flag as a symbol, and sends a message (not a nice one) regarding that which the flag represents. Obviously this isn't counting cases in which flags are "retired" and such.
Burning a book, on the other hand, is an act of destroying information. A book is more than just a symbol representing a state or institution. A book has content. Historically, book-burning has been a form of censorship and oppression for a long, long time. And even more annoyingly, it's almost always participated in by people who haven't even read the book they're burning.
Personally, I don't care what happens in either case, but I do think that both could be considered insensitive and offensive and if the intentions were pure, the people involved in both would realize that and look for a better way to handle it. Didn't the governer of New York offer to help find a different location for the mosque/community center?
Well, I'm no Muslim, but if I were in a position to put up a building (uh, probably a museum or something) that I wanted to and had a site on which to do so, and a bunch of people flipped out and protested my location for some reason that had nothing to do with me or anything I'd ever done or planned to do and that didn't have any actually practical considerations, I wouldn't say, "Well, these people are oh-so-very-offended, so I should work with them to reach some sort of compromise and get this built where it won't be offensive to them." More like the opposite. I'd probably become pretty stubborn. Maybe I'm just weird like that, but I can totally sympathize with someone else who reacts that way.
Oh, and in this case, man. I've seen videos where people are asking protesters how far away the place would have to be in order not to be offensive, and it was like a different answer every time. Really, it doesn't surprise me. Different people are offended by different things in different ways. And that's fine. But you don't have a right to not be offended.