Yes people are looking into it. The software has the capability to automatically add in support structure material based on the the orientation of the object to be printed. For the best use of this you'd need a support material extruder (with appropriate support material) and another head as the build extruder.
However, at the moment most of the Repraps in the wild only have a single head so they are making do with using the same plastic for build material as support structure with a fragile join so that the support can just be snapped off when you're finished.
Its not ideal but its better than nothing. I haven't heard a lot of talk about it lately but it was in the original roadmap for the 1.1 version to come between Darwin (1.0) and Mendel (2.0) so it seems to have slipped off the radar a bit.
I was looking for the page that had this roadmap for the future to point you at but it seems to have been moved since I last looked so here is a page with some of the ideas for future toolheads instead: [
reprap.org]. Ed Sells also has some good tables over two or three pages in the concluding chapters of his PhD thesis that could also be used as a roadmap outline for the next 2-3 years as well [
reprap.org]
The guys over at Bits From Bytes are experimenting with twin extruders so maybe it will become 'mainstream' next year :-) [
bitsfrombytes.co.uk]
