Microsoft is looking at OnLive Desktop at the moment to ensure that the licensing requirements are being met:
We are actively engaged with OnLive with the hope of bringing them into a properly licensed scenario, and we are committed to seeing this issue is resolved.
For those of you who are unsure, OnLive Desktop allows users to connect up to an instance of Windows from an iPad. This allows applications such as Outlook, Powepoint, Word etc... all to be used remotely as though the iPad was running a session of Windows 7.
The type of service is great as there is yet to a be a decent native version of Excel on the iPad for example. By utilising a virtual machine it allows the full functions of Excel and other apps to be more easily used.
Microsoft is "just checking" and working with OnLive to ensure that licensing is working. By saying that, they probably mean that it isn't and want a lot more money from them.
Full details of what can be done with the license can be found over on the Microsoft Blog.
Details of OnLive can be found over here.