What's the advantage to deploy 3D printing on IaaS
Most cloud models are based on virtual rather than physical services.

The closest thing I can think of as "IAAS" in the 3D printing space would be something like 3DHubs which connects people that have printer capacity with people that want to print.

The whole cloud 3D printing thing seem a bit questionable to how large/viable of a market it really is.  I know there are a LOT of people out there that want to make money off of (or at least defer the cost of) the printer they bought; but, the market seems over-saturated.  Heck, even UPS does it.

All the people that I know that use contract printing already have their own printer but contract out either for more volume, or a different material than they can print with their printer.  At work we have a printer; but, we go outside if we want volume (hundreds of pieces) but are not yet ready to commit to a mold.  When we go outside, we would only consider a trusted vetted supplier - not the cloud.