Visual Studio 2010 will be the Developer IDE for WSS 4.0 and SharePoint 2010.
It appears there is a Beta 2 already of SharePoint 2010 from this quote also:
"Make sure you have the beta 2 of Visual Studio 2010 and the beta 2 of SharePoint 2010 installed on 64-bit Windows Server 2008. Open Visual Studio 2010, click File, New Project, and then navigate to the SharePoint node in the Installed Templates section." Steve Fox, MSDN
Not backwards compatible
As stated in the SPSNYC presentation by Brian Maslowski VS2010 SharePoint tools WILL NOT be backwards compatible with WSS 3.0 and MOSS 2007. So for that you will have to continue to use Visual Studio 2007 and VSeWSS 1.3 CTP or possibly Visual Studio 2010 with the new WSPBuilder 2010 tools.
External References
Add Custom Assembly
