Re: Facebook Sweepstakes
I've won several wildfire-hosted-via-facebook sweepstakes. And a couple using some of the other middleman-app-via-facebook sweeps, and some using custom built in-house facebook apps, and all the othe various ways sweeps wind up on a facebook page. Like Amy said, Facebook is simply the platform where these live, either the 3rd party vendor (wildfire, etc) have developed a product they sell to companies looking to host giveaways without doing all the IT work in house, or the company has developed their own and are hosting it within their facebook space.
Wildfire is no different than ePrize or some of the other companies that specialize in sweepstakes promotions, they just happen to be one of the ones that specifically integrates well with facebook.