As I mentioned last month, VS 2008 fully supports building applications for .NET Framework 2.0... This is very important as it will take time for some hosters and IT organizations to fully deploy .NET Framework 3.5, but you don't want that to block you from taking full advantage of the cool features in VS 2008.
Today we released ASP.NET 2.0 AJAX Templates for VS2008. This release contains project templates for using Visual Studio 2008 or Visual Web Developer 2008 to create new web sites and web applications with ASP.NET AJAX Extensions features. The project templates contain specific references to assemblies in .NET Framework 2.0 and ASP.NET 2.0 AJAX Extensions 1.0.
Download the ASP.NET 2.0 AJAX Templates for VS2008!
Then, go to File->New Project and select .NET Framework 2.0 as the target runtime. That will filter down the options and you should see "AJAX 1.0-Enabled ASP.NET 2.0 Web Application". Select it.
Notice the assembly reference in web.config is fixed up to be the 1.0 version number...
<system.web> <pages> <controls> <add tagPrefix="asp" namespace="System.Web.UI" assembly="System.Web.Extensions, Version=1.0.61025.0, ...
Now you are all set up to get the power of developing with VS 2008, but target .NET Framework 2.0.
Please let me know if you have any questions or comments.
Speaking of VS 2008 enhancements for Web Developers, I also encourage you to check out the Web Deployment Project release for VS2008.. Web Deployment Projects (WDP) for Visual Studio 2008 - December 2007 CTP Released