http://www.imaging-resource.com/PRODS/olympus-e-m1/olympus-e-m1A.HTM
Via Image Sensors World
Quoted:-
"Low-pass filters, the lack thereof, and moiré
There's been a strong move in the camera industry lately to remove low-pass filters (aka anti-aliasing filters or LPFs) from cameras, in pursuit of greater image sharpness. The Olympus OM-D E-M1 is one of the latest camera models to join this trend.
At IR, we feel strongly that eliminating low-pass filters is a bad idea, and a mistake for the industry. While the vast majority of natural subjects aren't subject to aliasing and moiré issues, many man-made objects have the sort of regular patterns that trigger the problem.
The real problem is that once you've got moiré or color aliasing in your images, it can be very difficult, if not impossible, to remove."
"As noted above, these examples don't point a finger at Olympus alone: The same or worse can be found in the output from virtually any high-end camera built without an LPF."
They have their daily life example images to prove that they are right. Of course, as the most basic thing for digital sampling, the Nyquist theorem should NOT be violated!