MyFonts released an iPhone version of their WhatTheFont identification tool last week. It has a very simple and easy to use interface. You basically just take a picture of a font, crop and upload it, and it will run the characters through a recognition database and give you possible identities for your mystery font. Works well so far (at least it was able to recognize Futura above), but it will be interesting to see how it does with some more challenging typefaces.
Image via 20th Century Type