speakerphone face-up?

[mathiass]

We all know how the speakerphone kicks in when the phone is placed face-down... but is there a way to make it work face-up too? The speaker sounds just fine and even the 2nd mic works (sounds a bit muffled tho). One tweak could be to switch mics depending on how the phone is placed:

face-down: the usual functionality
face-up: same speakerphone, but use the main mic on the bottom of the screen part of the slider, rather than the mic on the bottom of the phone

I have no idea how to go about getting this done, but if enough people like it maybe a chef or someone smarter than I can get it done...