Microsoft has set three tiers of pricing for XNA developed titles, games may cost 200MS points ($2.50) for titles 50MB or less and 400 ($5) or 800MS points ($10) for titles that weigh in at a maximum of 150MB.
Microsoft is set to share up to 70% of profits from any XNA developed title. Microsoft has also revealed plans to help promote the more successful titles on the service. "If we help you sell an absolute ton of these, it's going to be up towards 30% [more of your total revenue]," Microsoft chief technology officer Chris Satchell told MTV Multiplayer. "If it's not doing so well, down towards 10%."
As Shacknews described, developers who choose to distribute titles via the Xbox Live Marketplace will not be able to opt out of royalty-cutting promotions. Creators must first agree to a common set of terms when adding a game to the service and, According to Microsoft, "the majority of sales and revenue a creator earns will be generated by our promotions."
Unfortunately, XNA Community Games will not include achievements and the service is structured so no game may be released for free, but we assume we'll see demos for each title.