How do I change my Field of View?

According to a question on the now defunct teamfortress2fort.com

It's in the Multiplayer tab of the options window

Yes you can! in console

fov 90

(~ = console that you need to enable in multiplayer options)

at least this worked for me :)

It now appears to be limited to 70 degrees for TF2, much to my annoyance (I play on a triple monitor setup with 15:4 aspect ratio, and everything is severely distorted at the edges of the screen).