See the latest interview with Pentax and this is what they tell:-
http://www.twice.com/article/472705-How_Much_Does_Size_Matter_In_Image_Sensors.php
via Blog reader VoiceOfReason
Quote:-
"In the Q camera, we've been working out the design for five years. It wasn't until the sensor for that camera was created that we felt there was a sensor good enough to match up with those lenses and that size body."
It is also said that:-
"So, I would narrow it down to size matters, but quality also matter. We feel that we're able to maximize the quality in that compact size with a combination of the image processing, and the lenses."
Pentax emphasized in the interview that whilst the sensor size is small, the image processing of the Q is extraordinary and the IQ of it will not be bad and is comparable to other high-end P&S DCs in the market. Well, let's see what will happen and actually how it will perform!