I've been thinking a fair bit lately about the whole Windows vs Mac OS X battle that has been raging ever since both operating systems were released. Whilst it is true that Windows is more open and freely customisable than Mac OS X, this comes at a great cost to me. You see, when I use Windows I spent so much time and effort customising it to my liking that I never got to actually do any real work in it. Hence, why Mac with its arguably more intuitive user interface out of the box is the one for me, as it just works pretty much perfectly for me with a few exceptions, those having to do with any graphics intensive gaming (blame Microsoft for a closed DirectX system) and Mission Control's dual screen functionality, or lack thereof.
I actually get things done without so many distractions, plus the window management system is way better in Mac, Mission Control being the Aero UI and Flip3D done right and actually useful.
What is worrying however is this new feature in Mac OS X Mountain Lion, Gatekeeper, which is ironically a trojan horse for Apples Xcode and App Store ecosystem.
Basically, it has three settings that control what happens when a .app is opened:
- Only from App Store - is what it says, only applications from the app store will be allowed to run, and anything else will cause OS X to literally scream "VIRUS!!!".

- Only from authorised sources - this is the default setting on all new installations and is kind of what worries me. With this setting, only applications that have been signed by an Apple-registered developer, who pays Apple $99 per year, every yea, will be allowed to run. This is good in a way but nonetheless still draconian and ensures apple gets a nice income from all developers of Mac software regardless of whether they're distributing through the Mac App Store or not. It also will mean that most FOSS will not be able to fall under this category, because it isn't compiled from the same developer/development team every time, locking out average users who want to take advantage of the security offered by Gatekeeper, as well as the wide range of software that is open source or free like Adium, VLC media player, Firefox, Google Chrome, AppleScripts, and any software developed on Google code and without Xcode. It could potentially kill the open source scene on the Mac, which would be incredibly sad and ironic, since one of the reason I moved to Mac was because of the quality of free software on the platform.
We might also see a similar thing to when Microsoft thought it'd be a good idea to quality control windows hardware drivers, and get vendors to sign their drivers. Unfortunately this didn't work well, with many of them including Toshiba refusing to sign a whole host of device drivers, and it didn't take into account end users hacking drivers to support similar devices. What if popular software vendors refuse to sign up with Apple?
Whilst this is unlikely to happen, it may still occur and is worth thinking about, especially since Mac OS X is a growing marketshare.

At the same time, Microsoft is making revolutionary changes to its platform, an open one at that, with the metro interface becoming the predominant way we are going to use Windows from now on. With the massive paradigm shift, I might need to switch to windows permanently to keep up with the mass PC market. Others could be in the same boat.
All this could happen, assuming that Apple's slowly closing ecosystem doesn't catch on like wildfire as it has in the past few years. Things like iCloud, iTunes, and iOS are essential to this.