From Microsoft Makes Open Specification Promise:
Microsoft made an irrevocable promise yesterday to not assert any of its patents against the implementation of some web based standards. ... So, MS is promising, in advance, not to assert patents over any standard that it helps to develop. This flies in the face of the patent hawk mantra that patents are "necessary to incentivize development." Truth be told, MS and others develop standards because they benefit from the existence of the standard itself, not some patent that they may some day receive.