Not if you know what to look for. I came across code that implements the metaphone algorithm (http://en.wikipedia.org/wiki/Metaphone) and used it for a sample project I started, but never finished, years ago (http://boston.conman.org/cgi-bin/location/location.cgi). It could be modified to allow free form text, instead of the text field for the city, pull-down for the state, but that's an implementation detail.

But the point is---code to check for misspellings already exists.