Chipworks' analyst Ray Fontaine published his impressions from small pixel presentations at IISW 2011. Actually, one of the most interesting presentations came from Ray himself and talked about 1.4um pixel reverse engineering revelations. The presentation and the paper are kindly made accessible on-line by Chipworks. The most impressive part for me was ST managing to fit color filters in cavities etched between the pixel metals (in mass production):
Another impressive job by ST is deep trench isolation between the pixels, while maintaining 50e-/s dark current at 60C (mass produced too, found in RIM handsets and tablets):
Many other interesting reverse engineering pictures are inside - highly recommended.
Thanks to RF for sending me the link!