The label control now allows you to output different text based upon browser type.  This could prove to be a powerful feature when there are browser specific differences. 
For example:
<asp:label id="MyLabel" runat="server"
      text="Default Text"
      mozilla:text="Hippie Browser"
      ie:text="Not Hippie Browser" />
In Firefox, it would display Hippie Browser.  In IE, it would display Not Hippie Browser.  Supposedly, you can specify this on just about any property now on any control.
Browser capabilities are now stored in .browser files in the %windows%\Microsoft.NET\Framework\version\CONFIG\Browsers folder.  By default, there are browser profiles for IE, Mozilla, Opera, AvantGo, WebTV, and a ton of device specific ones (phones).

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