There is a very good article which describes about the steps involved in creating WSP file from command prompt.
There are some new features Microsoft has introduced in ASP.NET 4.0 which consists some enchancements and some of them are real value added for Webforms.
You can set meta tags by using the Page.MetaKeywords and Page.MetaDescription page properties.
More control over view state by using the Control.ViewStateMode property for a page and for individual controls.
Easier ways to work with browser capabilities.
Support for using ASP.NET routing with Web Forms.
More control over generated IDs by using the Control.ClientIDMode roperty.
The ability to persist selected rows in data controls by using the GridView.EnablePersistedSelection and ListView.EnablePersistedSelection properties.
More control over the HTML that is rendered by the FormView and ListView controls.
Filtering support for data source controls by using the new QueryExtender control.
Charting support by using the new ASP.NET Chart control.(I love this really now I can get rid of OWC )
I liked personally some of the new features in .NET 4.0 and just want to share those.
The new String..IsNullOrWhiteSpace method indicates whether a string is null, empty, or consists only of white-space characters.
New Path.Combine method overloads enable you to combine file paths.
You can now enable lazy initialization for any custom type by wrapping the type inside a System.Lazy<(Of )>) class.
The compression algorithms for the System.IO.Compression.DeflateStream and System.IO.Compression.GZipStream classes have improved so that data that is already compressed is no longer inflated. Also, the 4-gigabyte size restriction for compressing streams has been removed.
You can download the beta version of VS.NET 2010
at the following location.