OK, so you’ve bought an iPhone and you love it (disclaimer: of course I love my family more than my iPhone). You’ve imported all your contacts from your old phone (I did it manually). Next you’ve added birthdays for all your contacts so that you will never forget their birthday again. And now you expect these birthdays to appear in the calendar of your iPhone…but they don’t!
What you need to do is open iCal on your Mac (you do have a Mac right?), enter preferences and check the “Show Birthdays calendar” option under “General”. Now sync your iPhone again and tada!