Kardashian wedding details

As reality star and fashion entrepreneur Kim Kardashian prepares to marry New Jersey Nets forward Kris Humphries Saturday, last-minute details have begun emerging.

The estimated 500 guests for the wedding, being held at an undisclosed location in Montecito, Calif., include Kardashian show-producer Ryan Seacrest; reality stars Nicole Richie and Kelly Osbourne; TV personality Maria Menounos; tennis champions Serena and Venus Williams; and "Dancing With the Stars' " Mark Ballas, who choreographed the bride and groom's first dance, Us Weekly reports.

The magazine said morning-show host Kelly Ripa sent her regrets, as did "American Idol" finalist Pia Toscano.

Singer-actress Demi Lovato, who turns 19 Saturday, told "Access Hollywood," "I'm so excited ... It's going to be my birthday and I get to spend it at Kim's wedding."

Because of their career schedules, the couple is not taking a honeymoon immediately, according to E! Online, which said Niche Media chairman Jason Binn will host a newlywed party for them in Manhattan on Aug. 31, designed by wedding planner Colin Cowie.

The nuptials were initially rumored to take place at the estate of Google chairman Eric Schmidt, and then at the neighboring mansion of venture capitalist Frank J. Caufield. Santa Barbara TV station KEYT identified only "a private estate on Sycamore Canyon Road."