These amounts are unknown and likely unknowable, which may help to explain why Mono's status is so uncertain. A month ago, for example, Microsoft applied for a patent on the .Net framework classes. Some observers pounced on the move as evidence of an abiding suspicion that the company intends to shut down competing implementations. Others noted that like IBM and others, Microsoft routinely acquires but rarely enforces patents. I don't think anyone knows how it will finally play out. It's an equation with too many variables, further convoluted by the recent renaming of Windows Server 2003 and de-emphasis of .Net as a platform.
A healthy software ecosystem has to create niches where commercial and open-source projects can thrive. Java does that, but is neither an open standard nor a first-class citizen of the Windows platform. The Common Language Infrastructure is, at least in theory, both. Whether theory will become practice is an important question that makes Project Mono worth watching.