Not much for me anyway.  There is no way I am going to jailbreak my iPhone just to have a Colemak layout on it.  Last year that was one of the lesser reasons I was waiting to buy one (the price being a bigger isssue and the lack of 3rd party apps being the other).  I had hoped that Apple would make it possible to easily rearrange the keys.  After all why not?  It's a virtual layout.  That's one of the strengths.  It's really stupid that you can't.  Anyway by now, I have Colemak layout well memorized and I have learned to live with and tap pretty fast with my thumbs the Qwerty layout on the iPhone (though yes it still irritates me that I can't have my favorite layout on there when I show stuff to people who ask me about my phone).

If this was free solid app being introduced into iTunes store as a way to advertise for this site with promo material on the arguments for using it for touch typing on a normal keyboard and directions to the Colemak.com website,  that would be huge!

How big is the set of those using a jail broken iPhone and using Colemak.  My guess is not big enough.

Would be interesting to see if having a period and comma readily accessible with on the wide keyboard view  helped my thumb speed and accuracy.   Right now the wide keyboard setups feel a little to spread out for Qwerty but I think that with Colemak it might be just the right spacing.

but yeah, it's about raising visibility.