For example you can do the following:
<asp:LabelAlthought probably not useful, when viewed the above code will display "Hello Internet Explorer" if you viewed the page with IE, "Hello Mozilla" if you viewed the page with Firefox, and etc...
IE:Text="Hello Internet Explorer"
Safari:Text="Hello Safari" />
The device filters use the same Browser Definition File Schema information that I shared in my HttpBrowserCapabilities entry.
Unfortuantely, I wasn't able to get the menu to look like I wanted in Safari using device filters, but it did enlighten me to the new feature.