The Gnome desktop environment developers have recently taken the decision to reengineer the Gnome desktop around the Mono framework. This decision has mainly been influenced by the main Mono developer Miguel de Icaza, who is a very vocal employee of Novell.
Reasonable doubt has been rased to whether or not Mono can actually be deployed freely. Mono itself is basically a free and halfway portable implementation of the .NET framework developed by Microsoft. However, the .NET framework itself is subject to a large amount of software patents, which cover the concepts used within the .NET framework. Since these are concepts and not individual implementations (which are covered by Copyright, which is certainly untouched by a reimplementation), they most likely also apply to the Mono framework.
To Novell itself, Icazas employer, this is not a significant problem, since Novell has closed a patent deal with Microsoft which undoubtedly also covers the .NET patents. However, all conventional Linux and Open Source vendors would not be able to distribute Gnome as it would be covered by the .NET patents Microsoft owns.
This amounts to an easy way for Novell to effectively lock in Gnome users to their own products. Gnome would no longer be a real Free Software project, even though the code remains freely available. It is expected that this type of patent issues will be raised many times, causing severe damage to the economy with the time. The only way of mitigation will be a transatlantic patent agreement which clarifies Art. 52 EPC: Software is not patentable.