Or you could do like Torvalds and get a Macbook Air but install another OS on it. Criticize the software all you want, the hardware is still damn good and at the top of what you can get.
Even if there was a few hundred dollar premium, keep it in perspective. How smart is it to be fretting over a few hundred bucks with respect to a tool that you will likely use for a year or two, for a significant % of your waking hours, and upon which you depend for your most of your income?
OS X Lion costs $29. Windows 7 costs $119-219, depending on which edition you get.
While it's possible to buy a machine without Windows, the selection tends to be quite limited, particularly for notebooks. Assembling your own from parts is an option for desktop machines, but again not really for notebooks.
Apple already contends that OS X can't legally run on generic PC hardware, and has already taken x86 Mac cloners to court over this and won, so they know they've got the law on their side when it comes to control of their OS, where it can run, and what can run it.
The next logical step is to take control of what can run on it. With the recent OS X "virus" scare, the issue has become all the more urgent, as the public's perception of its security has been damaged and a signed-app "solution" seems like the easiest way to restore confidence in it.
As far as requiring signed code goes, though, their other devices already all require it, so I'm assuming, based on their moves so far, that it isn't far off on the laptop/desktop end. That it's an option (on by default) in 10.8 makes me think that, one day, the option to run unsigned code in OS X will disappear entirely.