At the Portland Farmers market, I believe you can go to the information center and get tokens for your food stamps, which you can then use throughout the market.
Something similar at the larger markets here also. It is a voluntary program, so far.
The Farmer's Market I sell at is a start up operation and we are operating on a very thin shoe string. We don't really need much more than that, we pay for advertising and do group buys for things like produce bags and other packaging.
A requirement to be able to process food stamps at our operation would likely put us out of business. The location we set up at does not have electricity or telecomm capability and the cellular broadband here is the next thing to nonexistent. We would have no way other than paper to process the transaction and no way to verify the food stamp debit card.
As far as the new food safety act is concerned it will have an impact on farmer's markets, how much of an impact remains to be seen, so far I'm not overly pessimistic but I'm not jumping for joy about it.
The regulatory entities charged with making and enforcing the new rules have a pretty long lead time to promulgate the new requirements, 6+ months IIRC.