MVC 3 with Razor Views
Gaining momentum Large enhancements still landing Razor templating view engine DI enhancements jQuery validation improvements
Web Forms 4.0
Nicer control identifiers Tidier web.config Routing framework can be used - tidier URLs ClientIDMode - Auto .NET 3.5 behaviour - Inherit - Predictable - Structure based - Static - exactly as entered.
IIS Express 7.5
Far more capable than the existing built in server. + Support for SSL (even has self signed cert!) Support URL Rewriting rules Support custom security settings Support for web.config configuration Non administrative possible Almost everything IIS 7 has! Can be installed by the web platform installer.
Web Platform Installer
All in one app for installing MS tools/components. Popular open source projects and components WCF RIA Services Toolkit Where to find things - Nuget Strictly code stuff, DLLs - Web Platform Installers Whole products. - Visual Studio Extension Manager VS specific
Basic IDE for ASP.NET "Visual Studio Access Edition" Introduction to development. Simplified component model. Can install side-by-side Integrates database, Razor, Web Pages (Kind of like ASP classic) and deployment.