I also don't really understand why Ovi should be changed in any way. It is fine the way it is: offering a marketplace for "commercial" developers.

If the "noncommercial" developer needs a way to get donations, would some sort of a donation framework/library work? Developer could use library/framework developed by community & Nokia to add a simple way to donate from inside the app. It could be based on PayPal (or perhaps Nokia Money if it's possible and Nokia is interested on building (or helping to build) thing like this) or something like that. This dialog could pop up when the app is started for the first time and it could also be available through app settings.