I-Micronews reports that Samsung Electro-Mechanics presented a low cost through the wafer via interconnect technology for WL-CSP CMOS image sensors on recent DTIP conference on MEMS & MOEMS in Nice (France). A nice article explains the manufacturing process of the new Samsung package:

Another I-Micronews
article analyses Sony and Omnivision BSI technology and its problems.
Thanks to J.B. for the links.