Those of you who came to the WEB days a few weeks ago (WEB = Waikato Experience of Biology, for those who didn't) might remember me saying that the human family tree is quite a complex thing. Not only is it a branching tree, rather than the linear model of early palaeoanthropologists, but our understanding of the nature & relationships of the branches is a work in progress. (Which is what science is all about, after all! Contrary to a common misconception, science isn't about 'the truth' [whatever that is], and we constantly review & revise our models & hypotheses as new data come to hand.)
In that light I thought you might enjoy a couple of new posts by Brian Switek, on his blog Laelaps. The first, Mystery hominin turns into mystery hominoid, is an excellent example of just how our perceptions and interpretations can change. In this case, those interpretations were based on a few teeth & a jawbone (& teeth have got researchers into embarassing situations before, with 'Nebraska Man' being perhaps the best-known example).
The second, More hominin hype, is a brief comment on a 2001 BBC documentary which was recently added to YouTube. The focus of the doco is Kenyanthropus platyops (the name means the 'flat-faced man from Kenya'), a fossil described some years ago now by Maeve Leakey & her team. Kenyanthropus lived at around the same time as 'Lucy' (Australopithecus afarensis), but there's not a lot of fossil material associated with this genus & its position in our phylogeny is not at all clear (contrary to statements made in the video). The discussion thread is also good, not least because a couple of commentators offer links to possible human/chimp phylogenies for you to have a look at.