I'm sure you'd bring in a couple clients off the bat who might be looking for such a feature - generally speaking, unless they are hard into development and want several OS's to test a product or their own OS patches etc..., people will stick to one OS.
Serial console access. The ability to reboot on demand and monitor what's going on would be a big plus for any developer. I'd be a big fan of it. You would most likely be talking to the techy crowd. The novice server administrator wouldn't know what to do with it. I'd aim your advertisements at those in online software development, open source projects, and maybe application hosting.
The only issue would be giving these people so much power - power corrupts

and that's no exception in this case. You'll have to be careful in what support you offer these clients - people who create their own boot routines, and mess around with the kernel could be a real burden on support if you're not careful.
It would definately be a unique feature, and something i would buy (if I no longer hosted my own) simply for the convenience and piece of mind that I have nearly full control over my server.