C8 on 25 July 2009
There is no Flash or Silverlight support in the current Xbox dashboard (NXE). The ads you see have been there since NXE shipped and are just streaming video. The interactive ads (navigate to a different page with some controls) are a proprietary dashboard extension format. The same advertizing formats (images, videos, interative experiences) were, for the most part, supported in the old dashboard - though I don't think audio was supported there - and (IMO) the ads felt less prominent.
