ePhotozine compared the two newest m43 cameras, the G3 versus the E-P3: “Overall the Olympus PEN E-P3 gives warmer results, while the Panasonic Lumix G3 gives cooler, but also more neutral images. The G3 shows less noise, but also seems to show less detail than the E-P3, which is surprising considering the higher resolution 16 megapixel sensor in the Panasonic, you would expect to see more noise, but ideally more detail as well. The Olympus PEN E-P3 shows more detail in highlights and in shadow areas which means you should get better dynamic range in your photos.”
On their website you can see many image comparisons. Now the big question is:
The G3 is now slowly beeing delivered to worldwide stores. Check those direct search links to see the status at Amazon, Adorama, B&H, J&R, eBay. And those are the E-P3 preorder search links at Amazon, Adorama, B&H, J&R, eBay.