Hi,
I think you are just being confused about the use of the single file page model v. the code-behind model. Often in books I see that authors plump for the single file approach simply because it is easier to print (and maybe more readable)

Nothing has changed in .NET 4 - both models work the same and the book may well take the same approach as before. Personally I'd go with code-behind but it doesn't really matter. See the bottom of this link for a simple comparison:
http://msdn.microsoft.com/en-us/library/015103yb.aspx

>Oops! I didn't mean XAML. I meant the ASP code and C#.
>
>When you create a new website in ASP.NET for VS2010, it creates other files automatically. When I looked at the default page, I saw ASP content and other ASP code in the default page, and also site.master, and an About web form. I think I'd like to anticipate what the author will do in his new version of ASP.NET 4.0 Unleashed, basically.
>
>So, here I am with VS2010 open on my desktop and a book that is based on VS2008. Changes have happened since VS2008. I want to run VS2010 and use the examples in the book I have. Things are different. Now, I can easily strip down the defaulted pages and do them as the ASP.NET book directs, or adapt to the new way of doing things in VS2010. Okay, so what I am doing is just thinking out loud and perhaps expecting some comments on the new ways things are done in ASP.NET 4.0
>
>>I'm a bit confused why you're talking about XAML and ASP.NET. Do you mean HTML? You don't really use "ASP" code either.
>
>>You use a mix of C#, ASP.NET, and HTML, depending on what you're doing.