Windows 8 is a huge ad platform(community.advertising.microsoft.com)
community.advertising.microsoft.com
Windows 8 is a huge ad platform
http://community.advertising.microsoft.com/msa/en/global/b/blog/archive/2012/10/01/windows-8-ads-in-apps-concepts-agency-partners-advertising-week-2012.aspx
It is up to the publisher/developer if they are going to put ads in their apps. There are places where ads belong, and where they don't. The publisher/developer needs to take into consideration their target market, and if ads are acceptable.
Placing ads in my video-editor is likely not a good idea. I need the screen real-estate, and I'm in a highly focused state. The advertisers likely don't want to be there anyway. Same with when I'm building a powerpoint. But when I'm watching a video, looking at my calendar, etc. etc. Ads can be beneficial.
And no, I'm not in advertising.