
Even though developers must pay the same amount for both Apple's Store and Microsoft's Windows Market Place, there are two things which show Microsoft's greed:
Developers who submit free applications have to pay the registration fee, and in addition, the upgrades are considered as a new submission.
In other words, every time a developer updates his application, he has to pay $99 to Microsoft, even if it's a small update. Also, you can only send 5 applications per year.