Importing documents of any sort?
 

Is there a way to import documents into OmniGraffle for iPad from any other app?

I don't see any way to import PDFs or other formats into OmniGraffle for annotation.

It ain't meant for PDF annotation. Use GoodReader for that task. OG is a wire framing and diagramming tool that isn't even good for mind maps. At the most we might hope for outline import. Though iThoughts does that well enough.

You can copy/paste from graphics and text apps tho, naturally.