As it appears that it's basically the notification/alert functionality of the OS extended to a watch, I'm going to guess that feature touches too much of the core OS to be integrated into iOS without a great deal of help/work from Apple.

Bluetooth, except for a few profiles, is locked down on non-jailbroken iPhones and requires the manufacturer to jump through Apple's 'Made for iPhone' hoops and design in a authentication chip into the hardware.

Does anyone know if this is also true for developing bluetooth low energy devices or are they going to be more open about that?

I have a solution in the works to interface with a Jailbroken iPhone :) Should be up in the next two weeks.

Probably Apple.