If you are an alpha gamer, if you read blogs about games (or write one), participate in discussion forums, and attend game store events, or if you're new to the game trade, you should know about the strange terms the game industry uses to release new product.
Most of the 20,000 items we stock (compared to 4,000 at Costco) just show up when we order them. There are no street dates or release dates, thankfully. There just isn't need for fanfare for the vast majority of games out there. When a company does try to create excitement with a date when there is none, it's usually met with eye rolling and sarcasm from the buyers and sales reps out there. There is coordination that must go into timed releases, especially if you try to run a top store that gets everything on the street date (like ours). At the same time, some companies need dates but don't have them. For example, it looks like Fantasy Flight Games, the release date joke at our store, will soon have street dates for some of their new releases. Some games, including most of the FFG line, very much need a street date. Take that as a compliment FFG.
Fans of the hottest games rabidly await releases, and street dates help us manage the process. It gets product in early so we're not telling a dozen people the average arrival time of UPS. It ensures that competing stores won't take our sales because their UPS delivery arrives at 10am and ours arrives at 2pm. This happens. Street dates cut one way unfortunately. A Wal Mart that sells Magic early will get a finger waggle from Wizards of the Coast, while my WOTC account, and thus my entire business, would be in jeopardy if I broke the date.