DxOmark tested the [shoplink 16886]Panasonic LX5[shoplink 14796] sensor which is also the heart of the Olympus XZ-1. As you can see the LX5 is on par with the Samsung EX1/TL500 and behind the Canon S95 sensor.
P.S.: Olympus XZ-1 preorders at Amazon, Adorama, Amazon Deutschland, Amazon France and Amazon UK.