The Cowell kiss came after an intense performance by LaKisha of "This Ain't a Love Song."
He said that was so good, he could kiss her, and she motioned him to bring it on.
Officially, Bush's appearance was to thank the show and its viewers for raising $70 million to help children here and in Africa.
The Bushes ended, however, with the following folksy exchange:
George: "Say, Laura, you think I ought to sing something?
Laura: "I don't know, darling - they've already seen you dance."
The show's six remaining contestants all performed Bon Jovi songs, as he gave the usual advice about singing with sincerity and personality.
The riskiest performance was by Blake Lewis, who sported dark-dyed hair and beat-boxed on You Give Love a Bad Name. Bon Jovi, wearing a "Philly Soul" T-shirt, seemed skeptical it was going to work, but the judges heaped praise.
Bon Jovi might also have felt chagrined when 17-year-old Jordin Sparks gushed that her mom is just the biggest Bon Jovi fan.
Tonight, two of the finalists will get kicked of the I-land, because last week's big results "shocker" was that it'd be heartless to winnow the tribe during a special charity show.
The voting totals from both weeks will decide who'll make the final four.
Contact staff writer Peter Mucha at 215-854-4342 or firstname.lastname@example.org.