Check out the link at: http://www.problastusa.com/soda.htm
It gives some information concerning what soda (sodium bicarbonate) blast is.
I have considered it, and know that there is at least one place in town that uses this process, but still have to research it deeper.
The link provided was found by going to google and typing "soda blasting" if you are interested in doing more research. Another key-word you might consider using is "sodium bicarbonate blasting.
Ive seen it used a lot around our area on everything from airplanes , tractors and cars my son and I plan on using it on our projects. All media is a pain to clean up though and has its advantages and disadvantages soda blast will not damage glass chrome or rubber seals though if done by a compentent operator. I would ask for references and talk to them before deciding though.