It does indeed sound too good to be true, however I read the article and if it really does what it says it does, then: oh boy oh boy!

I think its a bit unfair to throw in Doom III as a testcase, since the average pc doesn't even run Doom III without having to set most options to minimal, but they do mention something about running a linux version of quake III on a Apple PowerBook. And with pretty good results too. Given the fact that quake is still used in benchmarks, I'd say its worth a few thumbs up!