Here's a look at the business end of the year's hottest celebrity mergers: Brangelina and TomKat, of course
Brad Pitt, Tom Cruise, ...
Credit: TomKat: Stuart Ramson/AP; Mr. and Mrs. Smith: Stephen Vaughn

Relationships in Hollywood, even those in which genuine emotions might actually be involved, have always been part romance, part business deal. But this year proved just how risky — and rewarding — hooking up can be in an era of tabloid frenzy.

Exhibit A: the Brad Pitt-Jennifer Aniston-Angelina Jolie affair. Bradifer’s unraveling also removed Jen from their promising production company, Plan B (Charlie and the Chocolate Factory), but Brangelina’s coupling may have boosted the $186 million gross of Mr. & Mrs. Smith by keeping the stars on magazine covers for weeks before and after the picture’s release.

On the other hand, there’s Exhibit B: Tom and Katie, a union whose pre-War of the Worlds/Batman Begins timing was so conspicuous, pundits wondered if the relationship truly was a PR-generating business arrangement. That changed once Cruise jumped Oprah’s couch — suddenly, they were wondering if his career had jumped the shark. Despite studio hand-wringing, it’s questionable if TomKat actually hurt their films; at $234 million, Worlds is Cruise’s biggest hit. But it also didn’t give them the bump they may have been expecting (career heat, enhanced public appeal) — unless you count the bundle of joy Holmes is now carrying.