I think open operating systems are good for the world. They unleash the creative energy of the world to create new applications that the core maintainers would never dream up. Wikis, blog software, web browsers, and TeX are just the tip of an iceberg of ground-breaking applications that wasn't developed, licensed, approved, or even known about by the maintainers of the operating systems they ran on.
However, quite a few closed operating systems have been good for the world, too. I dare say gaming consoles have made human life better. If that sounds too fun and not puritan enough, then think about GPS navigators. Heck, just think about consumer devices that have software. If you want to put software in a Ford, you can't just hand out memory sticks. You have to talk with Ford, and if they say no, that's that.
Additionally, closed systems are ordinary. Nobody has particularly up in arms about Sony disallowing arbitrary development for Playstations. Nobody has said that Ford is being anti-competitive to control the software on its system. So why Apple?
I can speculate about why people are upset about Apple, but there is a more important point to establish: it's their right to close their system if they want. It's difficult to predict whether the net result will be a better or worse system, but at any rate it's their system. If you think they should do something different, then try to persuade them. Let's stop shy of force, however. We shouldn't allow major government figures to just step in and rough up any company they please so long as they have a mob of people cheering them on.
This is not to say that I see no role for law in the software world. There are plenty of basic business principles that it is tremendously helpful for the government to enforce. Contract, ownership, non-disclosure agreements, copyright -- these are all useful institutions to build and enforce. Another are that is ripe for action is open document initiatives: insist that government agencies release documentation only in open formats that are easily reimplemented and widely available.
When it comes to application platforms, however, it's premature. The area is just too dynamic. Expect a decade at the minimum for a major government to work out a reasonable system of law and enforcement for something new. Minimum. I would expect more like 20-30, and ideally there would be several approaches tried in different parts of the world before a final choice is made about how the thing should be done. For now, leave application platforms alone. If the government wants to do anything, hold up platform owner's rights to be gatekeepers for the content on them. Platform owners can opt to do otherwise, but if they don't, everything will still be fine. Once in a while, we'll even see a platform like the Wii: thoroughly closed, yet very much good for the world.
Let the flowers bloom. The iPhone is still budding, and we don't even know yet how it's going to fare once the initial fad runs out.