None of this is really due to take effect for a while, though, from the sound of it. The year-old DVD+RW article claimed that support for that format wouldn't make it in until Longhorn, so it's likely that the same is true of the newly announced DVD-RW support. Still, it's good to see Microsoft keeping the playing field level and letting the market determine the winner of this standards war.
Of course, on that note, it's difficult to call it a standards war, really. The only thing the two competing formats can't do with one another's media is record to it. Big whoop. Imagine how toothless the VCR war would've been if Betamax machines could play VHS tapes and vice versa. The +/- DVD competition is a standards tiff.