Scott Guthrie and Somasegar have both announced the Visual Studio 2010 and .NET 4.0 will be delayed. How long the delay will be is unknown. In fact, March 22nd, 2010 was announced as the launched date. Nothing was stated specifically about moving this date; however, both indicated that the release would shift a few weeks.
On the positive side, the delay is partially a result of adding an additional public beta. Expectations are that there will be an additional public preview (public Release Candidate) in February–prior to the official release. This public RC will include a “go live” license, which in effect allows you to launch applications onto the web.