Rachel Uchitel -- Mistresses Have Birthdays Too

Tiger Woods' main woman he's not married to, Rachel Uchitel, celebrated her birthday in West Palm Beach, Fla. last night.



Uchitel partied it up at Pistache, a French bistro that we're told is run by a Uchitel family friend.

Rachel had originally planned a big bash at a Palm Beach club -- but opted against it when word got out.