As per the latest announcement on Scott Gu’s blog, the final release of VS 2010 and .NET Framework 4.0 has been delayed. These tools are currently in their Beta as posted here a couple of days ago - Visual Studio 2010 and .NET Framework 4 Beta 2 has been Released.
The primary reason for the delay is to buy some more time to work on the Beta 2 feedback collected from customers, specifically around the performance of the product.
During February 2010, a Release Candidate will be made available with these performance and other issues fixed. The goal of the RC will be to collect further feedback and depending on the work to be done, we can expect to hear the final date of release.
Quality first, always!