This is a comparison of four cameras.
Nikon D100 6 megapixels from 2002. CCD sensor (DSC images)
Olympus E-330 7.4 megapixels from 2006. NMOS sensor (P images with E-330 on the end)
Olympus E-410 10 megapixels from 2007. NMOS sensor (P images)
Pentax K20D 15 megapixels from 2007. CMOS sensor (IMG images)
Images processing in PS CS3 with 50% sharpening applied and equal chroma noise reduction.