I'm pretty sure the intake manifold can withstand being powder coated since an IM doesn't get hot enough to affect the coating. And it's basically a lump of aluminum, no moving parts to worry about (except the plastic T-VIS plate on a bigport IM, which would be melted off). But what about the throttle body? If I strip that down to the basic housing with butterfly & shaft, would it be OK being subjected to the high temps necessary for getting powder coating? Are there bearings inside which would get cooked out?

I'm not positive if there is anything that could be problematic or not but personally I would ceramic coat it. Ceramic is harder, more scratch resistant and it cleans super easy because of the hard low friction surface.http://matrixgarage.com/content/ceramic-coatings

Interesting, I hadn't thought about that. I suppose it also rejects heat. Would this also benefit the intake manifold? Well, most of the heat the IM will get is through the head. I would need one of those polypropylene IM gaskets the Honda guys are able to pick up for their B series builds.

Does ceramic coating involve heating up the item getting coated?

Can anyone confirm whether the 4A-GE TB has bearings that would be affected by high temps due to getting powder coated?

I have thermal barrier coatings and heat transfer coatings that actually conduct heat better than metal. I doubt it matters much on the intake.
I have ambient cure coatings and oven cure coatings. The intake would be fine with the ambient cure.