The following made-up scenarios very well illustrate the problems that Microsoft is facing. The first one reveals the real motives, which could not be truly concealed.

Microsoft, patents and the open source community

Dear Open Source Community,

You have been had.

We hadn't been doing too well lately. Vista sales aren't up to our previously over-inflated figures, we are still loosing money on that whole Xbox thing, and Dell, normally our favourite lapdog, is going to go and sell Linux on a home PC! Not good. So, we came up with an ingenious idea. Let us use these patents we spent so much money on getting, despite the fact everyone knows they are worthless and frivolous, and take on the open source community with them!

[...]

Regards,

Microsoft PR team [NOT REALLY]

The second one shows demonstrates the inability to act upon the expressed desire (or baseless threat).

IT Confidential: What If Microsoft Went Door To Door To Enforce Its Patents?

How would you feel if Steve Ballmer rang your doorbell and starting asking about the software that you used? It's not so far away from what Microsoft is trying to do with its latest patent claims.