I've seen Macs in loads of films and TV shows. A few off the top of my head:
- Entourage (all the way through the series, almost like a Mac history)
- The Devil Wears Prada (all Macs in the Runway offices)
- House (seen a MB Pro in a laboratory, House himself has one at home)
- Constantine (Rachel Weisz's character has a PowerBook G4)
- Knocked Up (several Macs throughout)
- I Am Legend (Mac Pros with Cinema Displays, MacBook Pro used by Will Smith)
- The OC (several throughout)
- The Omen (the photographer uses a PowerBook + Cinema Display)
- 24 (I think the good guys use them sometimes, bad guys get Alienwares

)
The list could go on forever. It's not so much that Apple pays for product placement - it's more that Apple Macs look the best so they're used more often on TV and film.