Microsoft Visual Studio 2010 will be available on MSDN May 18, 2009, and a general download available later for non MSDN subscribers.
EDIT: It is now available - we are downloading it and the .Net Framework 4 beta 1.
Microsoft Australia has pages up already showing the UI improvements.
There is also a PDF file available with information about Visual Studio 2010 here.
Some highlights from the information:
- .Net 4.0
- Cloud Development - Windows Azure which is basically utility computing where you pay by the hour for your usage.
- Parallel Development - Not sure if this only means PLINQ for .Net developers or if they are only talking about C++ devs.
- TDD Improvements - Editor changes for building test cases first, and then writing the code.
- ASP.NET - CSS grids and design surfaces changes, more Javascript debugging improvements.
- C++ Compiler - Lots of changes for C++ development, including MFC.
- Sharepoint templates
- New Project Templates
- Windows 7 - MFC updates for Ribbon UI, and WPF changes.
- Application Model Changes - Reverse existing codebases, and lots of changes in Architect Edition to support more model types (including Class Libraries finally).
- Test Runner - This is potentially huge as it allows testers to submit bug reports complete with callstacks and traces that you can actually use to resume an app at the error point to avoid the dreaded No Repro on bug reports. I have seen this demo and it is quite impressive. We will see how it actually works though.
And just in case you didn't know the entire UI is now driven by WPF. It does not look like a major overhaul, but we will see once the new beta is released.

I personally am still taking a wait and see approach. We all know we will HAVE to use it. There is no other serious development tool for .Net developers. The question for me is how painful is it going to be to get our designers working in it (they have already said the designer model is changed), and what does .Net 4 entail for changes.
We will be downloading the beta and testing it with the engine for sure. Expect many updates about this over the coming months. Not because you need it today, but you will in the future.