Thank you for thinking about minimising power drain of Bluetooth keyboard for iPhone. However, I expect that a factory could make it more sturdy and less bulky than a DIY awkward concept. I suppose that Apple should produce a version of iPhone with keyboard, and Nokia should have produced a version of N900 without keyboard. It would have been a nuisance, though, to modify operating system accordingly to work smoothly on the device. But experience of making two-or-three versions of operating system for different keyboard configurations would make it easier for future versions of operating system. Unfortunately, Nokia jumps quickly between different operating systems. But the teams which developed N9 and N950 might further the experience by continuing the tradition of releasing keyboardless and slider phones side-by-side.
Jailbreaking/hacking an operating system is not an activity I enjoy. It means that:
1. developers of the system spent their time hiding the system from the user, so that he would not be able to see the whole filesystem, or to change the configuration of the system (Bluetooth profiles is just one small example);
2. users spent their time devising a way to go around the locks, and configure the system to their tastes;
3. the finished product is awkward to use, fragile and patchy, underneath its shining exterior.
Let's take an example from non-computerised world.
1. Automobile which has been designed once, without thinking about possible successors; which can be serviced by its user; which can be taken apart and put together, modified; As all Model T Ford parts are standardized, even the novice owner can identify parts and make most repairs. This made the Model T Ford one of the most popular, affordable and enduring cars. From its introduction in 1908 until the final car was made in 1927, the T were one of the simplest, recognizable and enduring cars on the road. Today, they still are.
2. Automobile which is one of many within its series; which can be serviced only by authorised professionals; which has been designed as tamper-proof and modification-resistant.
Android... I dislike it. It's difficult to pinpoint one specific reason. Its touch interface just doesn't feel comfortable. Its camera is autofocusing every second, and there is no setting to turn it off. It has too many different versions coming out. CyanogenMod, while improving Android, increases fragmentation of the market.
It's not a tablet. It's an Android phone, and hopefully, not a fake. Would you care to share where exactly can I find the setting to change the way autofocus works? "Touch to focus" sounds better that the "continuous autofocus" I have experienced.
No, I haven't heard about the Galaxy Camera. But what will you say years later, when it will run only Android 4.1, and there will be the newest Android 7 released? And the latest version of Android will allow, for instance, 3D photographs, or some other novelty?

Dualboot... There is multiboot on N900, and it is possible to boot many different operating systems on it. Though I personally haven't tried it.
Best wishes.
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Per aspera ad astra...