Mac OS X' iCal has a Birthdays calendar which pulls birthdays you set in Address Book and displays them, and this works very nicely, but it doesn't satisfy my needs. First, because I manage birthdays differently, and second, because I sometimes have more than one birthday reminder for a single address book entry. (E.g. one address card for a family of two or more.)
I whipped up a simple PHP script that reads my text file and produces iCalendar output.
The red entries above are the result of the import.