Below you can see the front-view size comparison of the Panasonic ZS3 and Olympus E-PL2. The Panasonic ZS3 is clearly the smaller of the two cameras. Its body is 11mm narrower, 12 mm shorter and 9 mm thinner than the Olympus E-PL2.
The chart below depicts how two cameras compare with average dimensions of the cameras in their class.