Controlling Food Stamps?

Recently, there was some press surrounding the topic of NYC's Mayor, Michael Bloomberg, trying to pass legislation to prevent people from buying soda and other sugary drinks with food stamps.

There is much debate on what people are saying/thinking about this.  Some think that if there are restrictions on buying soda with food stamps, what's next?  Can the government and tax payers control what people buy with a government-funded program?

On the flip side, Bloomberg's goal is to help combat obesity, which plagues the poorer people that live in America.  One article I found said that nearly 40% of all people on food stamps are considered obese.

What do you think?  Do you think this is right for this restriction to pass?  And if not, why?