Wasn't there some pizza chain that had commercials like this? Domino's maybe? Where they had video of diners eating what they thought was fancy, high end pizza, and then they did the big Domino's reveal.
I'm a blogger, and I have many friends who are very well known in the blogging world and make good money through social media. I just blog for fun, but I do get approached by brands to promote their product. (I don't do reviews.) I've attended blogging conferences, and there are a lot of brands who are becoming very savvy in going after bloggers to promote their products.
But many brands also see women bloggers as silly and willing to do anything for a buck and a free meal, and I'm sure that's how ConAgra saw them. Unfortunately, the power of blogging is HUGE. Dooce tweeted about an issue with a washing machine, I believe, and it became a HUGE national deal.
I don't think this is the kind of promotion they were hoping for.
ETA- I just saw that it was Pizza Hut that did this. I'm sure there were just as many people who were upset and refused to sign released. All it takes is about 4 people with good reactions to get a TV commercial.