Meet Pippa Middleton, the Maid of Honor

March 8, 2011— -- When Kate Middleton stands at the altar of Westminster Abbey April 29, little sister Pippa will be by her side, as she so often is. But Middleton's maid of honor has a slightly different social standing than her sister.

"Pippa has a reputation as being the really fun one, slightly louder and more outgoing than Kate," Tatler magazine editor Catherine Ostler tells the Royal Diary. "She's a Chelsea party girl, almost to the extreme."

It is her job, after all. Pippa Middleton, 27, launched the Party Times, an online party magazine. She has it sorted. She can enjoy the fun and frolics of a royal lifestyle with her big sister Kate but doesn't have to turn up in the morning for palace duties.

But all that might change at the end of April, when Kate Middleton officially joins the royal family. Part of her official entourage will include a right hand woman. "The rumor is [Pippa] will become her lady-in-waiting," says Ostler.

The role of lady-in-waiting usually goes to a friend or a relative. Princess Diana and William's current stepmother, Camilla, both enlisted their sisters for the job.

Indeed, Pippa Middleton (Pippa is short for Philippa) is in the thick of the royal posse. She is often photographed with the young royal set: Princesses Beatrice and Eugenie, and Prince Harry's on-off girlfriend Chelsy Davy.

"I think it's very convenient for her social status that her sister is about to become one of the most famous people on the planet," ABC News' royal contributor Duncan Larcombe says.

Watch now to learn more about the youngest Middleton daughter, Pippa.