The announcement of the Micro Four Thirds "standard" has prompted some speculation about possible lens quality. Most of the focus with digital camera has been on the sensors, (size,pixel,manufacturers...) however a remarkable different IQ ( Image Quality) can be the result of using better lenses than the "kit" version supplied by the maker.
This is an example sent to me by a mate that works for a Pro Photo lab.
The two shots were taken at the same aperture/shutter speed/iso
Canon 450D body
The top is from the Canon kit lens , 18-55mm, the bottom is from a Carl Zeiss Planar 50mm 1.4.
Because of the compression the difference is not as clear as it is in print, but you should get the idea...
BTW, if you copy and paste the top shot onto yout desktop, you can enlarge it and see the difference a bit more clearly