How to Go After Dark Energy?

It's well known that dark energy is a mystery -- both for scientists, and apparently for funding agencies who are trying to figure out how best to learn more about this stuff that makes up about 73% of the energy of the universe. I haven't been paying close attention to the ins-and-outs of this saga (there are more rewarding ways to give yourself an ulcer), but last I had heard the National Academy of Sciences had given very high priority to a satellite observatory meant to pin down the properties of dark energy. This was the JDEM idea -- Joint Dark Energy Mission, where "joint" indicates a partnership between NASA and the Department of Energy. (They don't always play well together, but the Fermi satellite is a notable recent success.) Now, via Dan Vergano's Twitter feed, I see a story in Nature News to the effect that things have become ...