Back when I worked at Blockbuster, the official street dates were actualy Fridays. But because all the retail stores would put the games out for sale as soon as they got them, word eventualy came down that we were to do the same.
Now, if those same retailers were to break street date on a movie, they could recieve a fine of up to $50,000.00 and possibly loose access to selling ALL movies from that studio. (And when I say studio, I don't mean just the little ones. IE: break street date on a Miramax movie, and loose distribution for ALL Disney studios, break street on a New Line flick and loose distribution for ALL AOL-Time-Warner studios.)