I can visualize how it would look and work in practice, and that would be awesome. Though, like you point out, the actual creation of the bluetooth device and the issue of powering the board comes into play and makes it extremely difficult.

You may be able to take the bluetooth device from one of the wireless Pro keyboards and work from that.
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MacBook 2GHz Intel Core 2 Duo w/ 2GB DDR2 RAM & 120GB SATA 5400RPM HDD
Canon Rebel XTI
Google Cr-48 Beta Laptop