RIM Didn't Make Use of Newly Acquired Modular OS from QNX
RIM has made some very smart acquisitions in the last few years. Its browser in the old OS was terrible. So it bought Torch Mobile, maker of a mobile WebKit-based browser, and the browser in OS 6 and the PlayBook are considered massive improvements. In fact, the PlayBook browser is more HTML5-compliant than Internet Explorer and Firefox.
Likewise, RIM bought QNX, a mature, well-regarded embedded Unix operating system with more than 20 years of development and support. It's widely used in many embedded devices and equipment. RIM's stated plan was to first introduce QNX on the PlayBook and eventually unify it with the BlackBerry OS, so there would be one OS to rule them all.
As I said earlier, that plan has been pushed back. But more than that, at BlackBerry World, RIM announced that with an upcoming upgrade, Android apps would work unmodified on PlayBook. All that's needed is an application compatibility layer, which RIM will provide.
The QNX operating system is extremely modular. You can use it as the kernel and write an OS layer for almost anything on top of it. In theory, you could put iOS on top of it. That's how the PlayBook will get the BlackBerry e-mail and contact manager. RIM isn't rewriting those apps for QNX, they are just writing an application compatibility layer for QNX so the same app written for BlackBerry OS can run on the PlayBook.
This is all nice, but it really makes me wonder, why did they buy QNX in the first place? It looks like RIM is using it to piggyback on Android and BlackBerry OS. Either go full out QNX or go full out BlackBerry OS, but don't create confusion.