The new Olympus Pen E-P1 is a new four thirds camera which is very unique. It's an interchangable lens camera and adapters enable you to use lenses such as M mount Leitz, Nikon, Canon, Minolta, Pentax, Zeiss as well as all of the new and older OM Zuiko lenses that you might have around. However, when using these lenses you must focus manually.
It's a 12.3 megapixel camera with a stainless steel and aluminum body, also available in white. Presently two lenses are made for the E-P1, a 17 mm f 2.8 and a 14-42 f 3.5 zoom, equivalent to a 34mm and a 28-64mm. I'm certain there will be more lenses offered by Olympus.
Here I have mounted an old Zuiko 55mm f1.2 lens using an adapter. I have a few older OM lenses that will be fun to use on this camera.
I also have some PK mount lenses which I can use with a Pentax adapter.
The camera has no viewfinder but does have a large 3" viewing screen. A special viewfinder is available for use with the 17mm lens.
For an in depth review of the E-P1 check out Digital Photography Review at dpreview.com.