Now we are told that dark energy …

is not an illusion after all (New Scientist16 March 2011):

But new, more precise measurements of supernovae, taken by the Hubble Space Telescope, clash with the simplest version of the void model. That model could be made to fit previous supernova measurements and other cosmological data, but only if the local expansion rate is about 60 kilometres per second per megaparsec or less. (One megaparsec is 3.26 million light years.)

That was within the possible error of previous measurements, but the new, more precise measurements give an expansion rate of 74 kilometres per second per megaparsec, plus or minus 2.4.

“It looks more like it’s dark energy that’s pressing the gas pedal,” says Adam Riess of Johns Hopkins University in Baltimore, Maryland, who led the observations. The results appear in The Astrophysical Journal.

And I had only just learned to live with it as an illusion.