Sony officially told in an interview at http://www.amateurphotographer.co.uk that they will develop their own mirrorless system and that it will be better than the current Olympus and Panasonics MicroFourThirds solution.
“Yann Salmon-Legagneur, Sony’s Marketing Manager for Digital Imaging (Europe) told us that ‘of course’ Sony is interested in Micro Four Thirds, but ‘not the format itself, but the products that [are] being launched’. Recent Micro Four Thirds cameras from Olympus and Panasonic have ‘moved the industry’ he said.”
Olympus and Panasonic shouldn’t be scared, because:
a) Olympus and Panasonic are the only one for now to have such a system for REAL now!
b) Because in one or two year when Sony will effectively unveil such a system Panasonic and Olympus will already have a lot of experience, lenses, and probably better tecnology.