I was at Compute Midwest (a tech conference in Kansas City, Missouri) this past fall and saw a demo of this very thing by Autodesk's Andrew Hessel. He ordered some customized bacteria (maybe yeast? I don't exactly recall) with the conference title encoded and then sequenced into the microbes. It was very interesting to me that that level of manipulation is available to any of us, right now (even if it's not exactly useful).

It did bring up some concerns, though -- do we now have mail-order anthrax manufacturing? This isn't something I'm seriously worried about, but it does seem like something to consider in the future as this technology evolves.

Something else I just thought of while typing this is that this would make an awesomely sci-fi means of information storage. No need to remember a password, we've encoded your gut flora with your private key!