I'm attending a BUILD session on Windows Store, but it looks like they won't be answering the key question everyone has: Will Microsoft be charging developers a percentage on each app sold through the store as Apple does in its own App Store?
On Monday, Steven Sinofsky told me that Microsoft would not charge a fee, or vig, on each app sale. But after reviewing Microsoft's reviewer documentation, I see that there are different rules for legacy Windows applications and new, Metro-style apps. And while Microsoft won't force developers to adopt centralized licensing for legacy applications--PhotoShop being the canonical example--they will do so with Metro style apps. (Where apps must be licensed for use on 5 Windows PCs.)
So it's possible that this zero percent vig applies only to legacy applications and not new apps. And Microsoft is not discussing this yet.
There were a few useful details, however. For example, the Windows Store will be the only place where consumers can get Metro style apps for Windows 8. This will allow Microsoft to ensure a consistent and reliable/safe experience, and I think that's the right way to go. (Developers will be able to "side load" their own apps while in development for testing purposes of course.)
Microsoft will highlight apps in a Spotlight section in the store. These will be GREAT apps, not apps whose placement is paid for by their makers. It will be editorially curated. There are various category sections too, including Games, Social, Entertainment, Photos, Music & Videos, Books & Reference, and News.
Developers are in charge of pricing, using price tiers (not announced). They can use features like Trial Mode and in-app purchasing; their choice.
More info as it arrives. Some more shots: