Ashlee & Pete Say "I Do" in Sunset Ceremony

In a sunset ceremony at the home of her parents, pop star Ashlee Simpson, the little sister of Jessica Simpson, walked down the aisle with Fall Out Boy bassist Pete Wentz.

Around noon on Saturday, the groom arrived via limo at the Encinco, Calif., home of Ashlee's dad Joe Simpson, who also officiated over the non-denominational ceremony under white tents.

Big sis Jess, who arrived with on-off beau Tony Romo before noon in the Employee of the Month star's Range Rover, was maid of honor. According to reports, Pete's bulldog Hemingway served as ring-bearer.

Also in attendance were Nicole Richie and her rocker babydaddy Joel Madden. Wearing jeans to the event were the other members of Fall Out Boy. Scrubs star Donald Faison along with girlfriend, Jess' former assistant CaCee Cobb, were there for the blessed event.

Sources inside the wedding say the bridesmaids wore Vera Wang gowns, while Ashlee wore an ivory gown by Monique Lhuillier.

The event was catered by celeb chef Wolfgang Puck, whose staff began to arrive on the scene around 3pm PT.

Around 5:30pm PT, the approximately 150 guests enjoyed a cocktail pre-wedding party. And shortly before 10pm, shuttle buses began to leave the Simpson house for those guests unable to party through the night.

One wedding VIP who definitely won't be boozing it up tonight is the bride, who sources tell OK! finally revealed her pregnancy to everyone at the reception. Weeks ago, OK! was the first to report that the couple were expecting a baby — a story that both Ashlee and Pete danced around on talk shows and in interviews.