[maaaats]

Is the 451 a reference to something?

[jvdh]

Yes, Fahrenheit 451 by Ray Bradbury.

A dystopian novel about a world where all books are banned and fire squads roam around to burn them.

[corobo]

Going by something someone has put on wikipedia "A reference to the 1953 dystopian novel Fahrenheit 451, where books are outlawed".

On that note it looks like Microsoft have already dibs'd 451 for an Exchange ActiveSync redirect anyway.

[dagw]

Almost certainly Ray Bradbury's book Fahrenheit 451