Credit: Denise Truscello/

A small, intimate affair for Kim Kardashian and Kris Humphries' Aug. 20 wedding? As if!

The new Us Weekly, on stands Wednesday, has the latest info on this summer's biggest wedding -- including the A-listers expected to attend the ceremony for the reality starlet, 30, and her NBA hunk, 26.

Among the 500 invited, according to insiders: tennis champs Serena and Venus Williams, Nicole Richie, Ryan Seacrest (executive producer of the Kardashian clan's reality shows), fellow E! star Kelly Osbourne, Kim's bestie La La Vazquez and NBC's Maria Menounos.

But not every star in Hollywood was able to clear their calendar for the nuptial bash. Kelly Ripa, who's going to be out of town on the 20th, sent her regrets; American Idol also-ran Pia Toscano (Kardashian wanted her to perform) also declined.

But Toscano's man, Dancing with the Stars' Mark Ballas, is a big part of the wedding planning: He worked with the bride and groom to choreograph the first dance!

For much more on the last-minute wedding prep -- the $20,000 cake, the last-minute dress decision, and how Princess Beatrice hooked the couple up with an incredible wedding venue -- pick up the new Us Weekly, out today!