Serious compacts posted a mirrorless size comparison (well done!). Images and text below are from Amin Sabet (please visit SeriousCompact to see the full article).
Above (left to right): Olympus mZD 14-42mm lens (kit zoom for Olympus Micro 4/3 cameras, shown collapsed), Sony NEX 18-55mm lens (kit zoom for Sony NEX cameras), Panasonic 14-45mm lens (kit zoom for Panasonic G1 and GF1), Panasonic 14-42mm lens (kit zoom for Panasonic G2 and G10), Samsung NX 18-55 (kit zoom for Samsung NX10)
Above (left to right): Sony NEX 16mm f/2.8, Samsung 30mm f/2, Panasonic 20mm f/1.7.
Above (left to right): Olympus E-PL1 with Olympus mZD 14-42 (collapsed), Sony NEX5 with Sony 18-55, Panasonic GF1 with Panasonic 14-42 (Sorry, wrong kit lens pictured; should have been the 14-45, which is slightly smaller as shown in the first image in this post)
Above (left to right): Panasonic GF1 with Panasonic 20mm f/1.7, [shoplink 3003]Sony NEX5[/shoplink] with Sony 16mm f/2.8, Olympus E-PL1 with Panasonic 20mm f/1.7
RiceHigh compared the NEX cameras with the most compact MFT cameras: “If Size Really Matters, What’s the Meaning of Micro-4/3 Now?”