Microsoft is on tap to talk publicly about and show off Windows 7 at two of its upcoming tech conferences this fall. But that does not mean the Windows team necessarily will be distributing bits at those shows.
Along with many other Microsoft watchers, developers and customers, I have been assuming Microsoft was going to provide attendees of its late October Professional Developers Conference (PDC) – or at least its early November Windows Hardware Engineering Conference (WinHEC) — with early Windows 7 bits. But according to new information I’ve received from sources that have asked not to be named, Microsoft is not planning to make Beta 1 of Windows 7 available until mid-December.

Source- zdnet.com