These posts have some information:
http://blogs.msdn.com/b/windowsstore/ar ... store.aspxhttp://msdn.microsoft.com/en-us/library ... 94058.aspxhttp://www.theverge.com/microsoft/2012/ ... -windows-8Cost is going to be $49/year.
Right now they are only accepting submissions of free Metro apps. Desktop apps cannot be submitted and I have no idea when that will change.
Quote:
b. Desktop App Submission. You may not submit desktop apps to the pre-release version of the Windows Store. Desktop apps are any apps built using APIs other than the APIs for Metro style apps that run on Windows 8.