The technology has significantly been improved since the the 80-90's. It is much more easier to capture a signal from an old device using high voltage. But this seems to be the first demonstration in the open litterature of this kind of vulnerability in modern keyboards (and wireless keyboards, considering the wireless communication as secure). Moreover, there is 4 different ways to recover the keystrokes and it concerns USB keyboards as well. So basically, yes I think it's new (or at least applied to modern keyboards)

The demonstration given by Martin Vuagnoux and Sylvain Pasini from the LASEC/EPFL has already been slashdotted (see http://hardware.slashdot.org/article.pl?sid=08/10/20/1248234&from=rss) in october 2008. You can see the videos of the experiment on http://lasecwww.epfl.ch/keyboard