Take a look at the micro 4/3 by both panasonic and olympus. Not the best for action type photos but good for outdoors. General consensus is that the olympus line has better out of camera jpeg images (meaning you don't have to do a lot of post processing). Samsung and Sony have some mirrorless cameras as well, however, lenses are proprietary. Lenses in Panasonic and Olympus are interchangeable. Voigtlander, noktor and Schneider Kreuznach have announced that they will be manufacturing m4/3 lenses as well. I've got an olympus. Preferred it because the image stabilization is in the body and not the lens, while the Panasonic has the stabilization in the lenses. With fairly inexpensive adaptors, you can use legacy lenses from virtually any manufacturer, though you'll lose all the auto settings with them.
http://www.mu-43.com/
http://www.four-thirds.org/en/microft/index.html
As far as pricing goes, epl-1 body, 17mm, 14-42mm, and 40-150mm lenses for a total of right at $725. The only thing that I would change about my set up is having some faster lenses.