Flipboard supports sending links to Instapaper. Just enable it in the Settings app, Flipboard, Experimental.
They’ve actually supported this since the first release, but since a lot of people don’t think to look in the Settings app, I keep seeing people publicly asking them to add this feature that they already have.
Flipboard is awesome, by the way. I never thought I’d find a way to browse my awful Facebook news feed tolerably, but with Flipboard, I can just check in every few weeks for a quick skim to see how fat all of my high-school classmates got (as I rest the iPad on my own gut).
(It’s also great for The Economist and other publications.)