There is a cool preview download centre up that uses Silverlight:

http://preview.microsoft.com/downloads/HomePage.aspx 

First glances it has:

• Menu in top right written in Silverlight
• The Popular and New Downloads tables are Silverlight
• The Browse Downloads is definitely the best use with a cool interaction when moving through the alphabet

Does seem very slow but that is probably because it is in Preview and not on full hosting infrastructure (guessing that anyway)