My reading of the patent situation is this: Open source developers are free to use the specs, but if -anyone- -ever- makes -any- money out of the open source software that entity will likely be sued out of existence. That doesn't sound like a very practical olive branch for an open source community that relies on commercial entities for distribution. Even putting up Google Adwords on the project's home page or hosting on sourceforge would likely infringe.
This seems more like a promise to in-house IT groups who are already Microsoft cutomers, rather than a general promise to open source developers.

Some of the stuff as far as I know in Ubuntu that is patented or legally protected by Microsoft would be certain media player extensions etc that are not available on a "out of the box" download of Ubuntu. To make it fully compatible they would have to either work together or somehow work around it, of course the working together isn't going to happen lol.

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