Mark Shuttleworth has reacted to Steve Ballmer's goofy Linux commentary with considerable aplomb (and not the splenetic fervor I sometimes spew :-). Microsoft can't seem to get it out of its collective mind that open-source developers care about intellectual property (even if we don't always call it that) as much as proprietary developers do. We just opt to share it rather than to horde it.
Intellectual property is something the free software community takes very, very seriously. There is a perception that the free software is somehow riding on the coattails of the real industry or somehow avoids intellectual property laws.
The contrary is actually the case. Mark cites Firefox and Xen as two areas where Microsoft - and the proprietary world - has actually copied the open-source world.
Which leads to Mark's most interesting comment: Microsoft is a pirate that trades on others' IP to the tune of over $1 billion each year:
Microsoft settles an average of one billion dollars in IP claims a year. Microsoft trades on IP violations all the time. It seems to wrong for them to use that same framework against open source.
Proof positive of wrongdoing? Of course not. Rather, it's proof positive that the system is broken to Microsoft's and open source's detriment. The difference, however, is that the open-source world doesn't go around throwing stones at Microsoft over IP infringement. We've got better things to do. Like serve customers.