My script has the same problem with special characters. Here's how I handle it:

Google Maps doesn't care about things like apartment numbers, business names, and other stuff in the address -- what it really wants is street addresses and zip codes (or city/state). My address book entries are formatted so that the first line is the street address, and subsequent lines contain information like apartment/suite numbers, floors, etc.

Rob moved my submission notes to be comments in the script itself -- in there, it states that my script removes everything from the address after the first line feed before building the URL to submit to Google. So presumably, you can put all the special characters you want in there, just not on the first line!

I understand if this isn't the way everybody formats their addresses -- just my $0.02.

Quick note -- just to clarify, you can have multiple-line entries in each field of the address in Address Book. My address book entries have multi-line entries in the "Street" field (where lines after the first contain apartments, floors, etc) -- the script strips this other stuff out, and just uses whatever's in the first line of the street field.