Why doesn't VS 2008 display extension methods in Intellisense for String class

Question

Since String implements IEnumerable, I was expecting to see the Enumerable extension methods in Intellisense, for example, when typing the period in

Answer 1

For info, this has changed in VS2010 (in beta 2, at least). It looks like this filtering has been removed (presumably it caused too much confusion), and the methods are now visible, along with the extension-method glyph.