This is the first in a three part series related to HTML encoding blocks, aka the <%: ... %> syntax.
Html Encoding Code Blocks With ASP.NET 4
Html Encoding Nuggets With ASP.NET MVC 2
Using AntiXss as the default encoder for ASP.NET
One great new feature being introduced in ASP.NET 4 is a new code block (often called a Code Nugget by members of the Visual Web Developer team) syntax which provides a convenient means to HTML encode output in an ASPX page or view. <%: CodeExpression %>