I'll leave the description of the discovery and its implications to an expert as PZ Myers at Pharyngula [Darwinius masillae].
I will however, say just one thing: the media has ridiculously exaggerated this finding. "Missing link"? Of course not. Nobody uses that "concept" in evolution; in fact I bet that only (some) "science journalists" do, which is just misleading to the general public.
Evolution is not a simple chain.
Notably, the article has generated a lot of controversy and discussion regarding its quality, and again has put PLoS ONE's 'peer review' system up for questioning [see Brian Switek's review: Poor, poor Ida, Or: "Overselling an Adapid", especially the comment's section].
Anyway, here's the original reference of the finding:
Franzen et al. (2009) Complete Primate Skeleton from the Middle Eocene of Messel in Germany: Morphology and Paleobiology. PLoS ONE 4(5): e5723 (image is from this article).
Ok, back to preparing my qualification exam.
Cheers!

