Mick Hartley

Carl Zimmer is probably the best man to go to for the lowdown on the new hominid find from Ethiopia. 

Meet Ardipithecus.
This introduction has been a long time coming. Some 4.4 million years ago, a hominid now known as Ardipithecus ramidus lived in what were then forests in Ethiopia. Fifteen years ago, Tim White of Berkeley and a team of Ethiopian and American scientists published the first account of Ardipithecus, which they had just discovered. But it was just a preliminary report, and White promised more details later, once he and his colleagues had carefully prepared and analyzed all the fossils they had unearthed. “Later,” it turned out, meant 15 years. 

More at National Geographic:

"What Ardi tells us is there was this vast intermediate stage in our evolution that nobody knew about," said Owen Lovejoy, an anatomist at Kent State University in Ohio, who analyzed Ardi's bones below the neck. "It changes everything."

And, if you're really serious about this, here's the full deal at Science Magazine. Free, but registration required.