In the age of Facebook, it's kind of hard to miss a birthday. But for your really good friends, a simple "Happy Birthday!" on Facebook may not be enough. Instead of going through your entire friends list to mark their birthdays on your smartphone's calendar, you can make things much easier by exporting the dates from Facebook. Just head to the "Events" section of your profile, and click the "Birthdays" link at the bottom of the page. Finally, click on "Export Birthdays" at the bottom of that page to send out the info to your iCal. From there, you can export again to plug in the dates to Entourage or Google Calendar.
Alternatively, you can have Facebook send you a weekly email of all upcoming birthdays so you don't miss a thing. Just head to Account > Account Settings > Notifications > Facebook and check the box that says "Has a birthday coming up (weekly email)."