Las Vegas Knows About Loyalty

I would have thought airlines--and their freqent flyers programs--were the masters of loyalty programs. But experts tell me a Vegas casino company--Harrah's Entertainment--does it better than anyone. I wonder.
Las Vegas already has sex and gambling on its side--why does it need a rewards program? What makes you loyal--freebies, service, fruit baskets or what?
Thisis what the Harrah's people say works: can you spell S-L-O-T-S.
http://www.adweek.com/aw/national/article_display.jsp?vnu_content_id=1003641333

Just today the news came that Macy's department store is getting a loyalty program going---and Coke's My Rewards program is going gangbusters, even though you need to drink about a hundred Cokes to get a T-shirt. Apparently loyalty works. Or is it an elaborate con job?