"All I know is what I heard on NPR" - assuming it's the same
thing. (I thought it was U of Kansas.) It's supposed to be in Phys.
Rev. Letters soon if not already.
The isotropic cosmological models we usually apply are just the
simplest ones general relativity provides. There are cosmological
solutions of Einstein's equations which aren't the same in all
directions. & curvature of space-time in Einstein's theory can affect
polarizations of EM waves. Whether the reported observations will hold
up, & if so whether they can fit into some plausible relativistic model,
remains to be seen. But so far it doesn't sound to me as if anything of
paradigm-destroying magnitude has happened.