Steve Jobs famously said we live in a post-PC era, but you’ll pry my desktop operating system out of my cold dead hands.

There’s a disturbing push to turn our desktop computers into overgrown tablets, whether we like it or not. We’ve recently seen the release of Mac OS 10.8 aka “Mountain Lion” and it continues Apple’s relentless push to blur the line between Macs and iPads. The move might appeal to fresh iGadget converts looking for cross-platform consistency, but old-school Mac users are less likely to be impressed.

Previously Mac OS 10.7 “Lion” saw the introduction of an iOS-style App Store for managing desktop applications. Many people saw this as the First Horseman of the iOS Apocalypse and feared that Apple would move to lock down Mac OS even further the same way it rules iOS with an iron fist. The release of Lion also saw the introduction of full-screen mode for some applications which slavishly copied iOS design concepts even though they often didn’t make sense in a multi-tasking desktop environment. There were lots of other little iPad-style changes which seemed to put style before functionality.

Apple has continued the iPad-ification of the Mac with Mountain Lion, although this time around it feels like less of a shock to the system than the leap from Snow Leopard to Lion. With Mountain Lion at least some of the new iPad-style additions are actually functional rather than simply cosmetic. The iOS notification system and dropdown menu (an idea which Apple “borrowed” from Android) has been brought across to the desktop. iCloud, iMessage and Reminders have also been integrated into Mountain Lion. They still need work, but these additions clearly have the potential to be useful rather than simply iCandy.

While Apple tends to be a trendsetter in the mobile space, it’s actually Microsoft which is leading the charge to merge desktop and tablet interfaces. The upcoming Windows 8 sports the tile-based Metro UI interface which has been seconded from Windows Phone 7. By the end of the year you’ll see Metro on Windows 8-based desktops, notebooks, tablets and smartphones. As with Apple’s efforts, Metro seems more practical on a touchscreen handheld gadget than on a desktop computer.

What’s interesting with Metro and Windows 8 is that Microsoft has taken the extra step baking touchscreen compatibility into desktop versions of Windows. If your desktop or notebook computer is blessed with a multi-touch display, you can tap, flick, pinch and scroll on the screen just like a tablet. Such functionality was available for Windows 7 but we only saw a handful of compatible devices and some like the Acer Iconia dual-touchscreen notebook were too cumbersome to be taken seriously.

Metro could help drive the take up of touchscreen desktops and it seems inevitable that Apple will eventually go down this path as iPads and Macs merge into the one touchscreen platform. Yet it remains to be seen if that’s what people actually want from their computers. Some of us actually prefer to put aside our touchscreen gadgets when it comes time to actually get some work done. Microsoft and Apple might have touchy-feely plans for the future, but some of us would prefer they keep their hands off our computers.