As Image Sensor blogger from Japan noticed, IEDM 2009 program has an interesting paper showing unstoppable Sony push to ever smaller pixels:
0.9um Pitch Pixel CMOS Image Sensor Design Methodology
K. Itonaga, K. Mizuta, T. Kataoka, M. Yanagita, S. Yamauchi, H. Ikeda, T. Haruta, S. Matsumoto, M. Harasawa, T. Matsuda, A. Matsumoto, I. Mizuno, T. Kameshima, I. Sugiura, T. Umebayashi, K. Ohno, T. Hirayama, Sony Corporation
"We proposed the constant-light-diffraction-scaling methodology in order to design the CMOS image sensor(CIS). We developed a high performance guideline, and verified it using CISs with various pixel pitches and number of metal wiring layers. Using this guideline, we realized the first ever successful fabrication of 1.12 and 0.9um pitch CISs."