The problem is a lot of stores, both GW and Independents are giving out conflicting information. That leaves us completely in the dark on who to believe. There are stores saying they will have a store copy of the rulebook for us to preview, while others say they are only going to get a small preview of the upcoming rules changes. One thing for certain, pre-orders are likely to start on the 23rd.
Here is the lastest rumor on the subject.
Quick update, stores will probably not have a copy of the book at the 23rd. Minigames which demonstrate biggest rulechanges will available, so you can experience them. No drooling over the book, though.