No comment and how to still tell the truth
I recently had a discussion with a fantastically brilliant past client of mine named Sam Gur, who is the CEO of Phytobase, which produces amazing organic chocolates targeted at women. Their latest chocolate is called Amoriss and one of the amazing things about Sam is that he's so committed to only producing great products, and his company is a little like Willie Wonka's in that it has an astounding research team that bigger players in the market like Hersheys or Mars would love to have.
The downside to being "Willie-Wonka-esque" is that Sam has to be really mindful of when reporters ask him about how he came to invent some of the chocolates they currently have. (Since he's not a client anymore, I can honestly say that the Chocolissima is truly the best chocolate I've ever had, but back to the point!) The problem is if you're in a competitive space, how much do you reveal about your "secret" ingredients before you've revealed enough for your competitors to figure it out as well.
The same thing on a bigger scale has held true for many years with the company Adobe and their proprietary PDF format. I write about that for PlanetPDF.com and it's still an ongoing issue.
The question is really how much to reveal before you've revealed too much and how to talk to a reporter about that specifically. My advice is to simply be truthful. If asked a question that you feel is going to reveal something that will give an advantage to your competitor - then don't reveal it. You don't have to be rude, you can simply say something like, "Well, I would like to answer that, but because of the competitive market we're in I can't do that right now." If the reporter continues to press, you can simply say that you appreciate the question very much, but that you're not going to be able to answer it at that time.
Honesty, authenticity, truthfulness are not just good buzz words in kindergarten, they actually are the only buzz words we all really need to try to live up to.