Chipworks published an interesting analysis based on its reverse engineering of 2012 models of mobile phones and tablets. The chart below is based on the non-representative set of teared down devices:
Another interesting observation is that "All of OmniVision’s devices are back illuminated, while all of Aptina’s and Toshiba’s are front illuminated. Sony and Samsung had a mix of front and back illuminated devices winning primary camera sockets (although the majority of sensors from both companies are back illuminated)."
There is a lot of other interesting data in the Chipworks article, well worth reading. Thanks to PD for the link!