Hobbits may have evolved from H. habilis

This article has a good description of recent results based on foot structure.  It also has a family tree diagram with Hobbits included. 





Palaeoanthropology: Homo floresiensis: from head to toe : Article : Nature

These features suggest that H. floresiensis evolved from a species that was anatomically more primitive than classic H. erectus from Asia. One possibility (Fig. 2) is that H. floresiensis evolved from H. habilis, whose skeleton is poorly known but is australopith-like in many respects. Another is that H. floresiensis descended from an earlier type of H. erectus, whose body may have been much less modern than we currently credit, and which perhaps deserves a separate species designation (H. ergaster).

Hobbit on NOVA

The show provides an excellent summary of the findings.
See it in Quicktime, here:

NOVA | Alien From Earth | Watch the Program | PBS

Hobbit Feet

Flores 'hobbit' walked more like a clown than Frodo - being-human - 16 April 2008 - New Scientist

And because of their long feet, H. floresiensis probably had to bend its knee further back than modern humans do, resulting in a sort of high-stepped gait. "You would watch these hobbits walk and say they're walking a little funny," Jungers says