It's a marketing-proven fact that a celebrity's endorsement of a product helps improve sales of that product. It's also been documented that a celebrity's endorsement of a product for charity can also help sell that product. Paul Newman is probably the best example of success in this vein.
NPR provided a good example of what goes on behind the scenes when a celebrity and business want to put out a new product linked to charity with a story on Pat Boone and his getting behind a new meat company. Check out the article for some good lessons for those considering the same.