The Wedding Singer.

Tom Cruise and Katie Holmes have asked American Idol’s Katharine McPhee to sing at their nuptials, says http://www.contactmusic.com/. Which shouldn’t be all that surprising, given the rumors that Katharine was, at one point, either a Scientologist herself or at least dating one (depends which version of the story you believe). It’s rumored that Katie met the singer at Los Angeles’ Church of Scientology and followed her progress in the American Idol competition week after week. After Katharine lost to Taylor Hicks last week, Tom and Katie reportedly, and on down low, contacted Kat and asked her to sing at their ceremony.

"Tom and Katie have become Katharine's biggest fans. They think she's destined to become a singing legend," a source close to the couple says. Probably so, if she actually gets to sing at the Cruise-Holmes affair… and certainly beats co-starring in a film like From Justin to Kelly.