Folks, we have a winner! Matthew Shapiro did it piecemeal; he figured out it was a CO2 mount... that was half the battle. Then he needed to sort out who made it.
I had a lot of great guesses (and I bet some engineers can use those stabs as ideas for bike solutions... like an aero cable router). The maker: Profile Design. I saw this in a new 2009 catalog (though it's not on the website... your best bet is to ask your local retailer to stock 'em) and I asked to see one. I was thoroughly impressed. But like I said, it lacked the sex appeal of all the carbon stuff that goes into the mags.
It mounts vertically between your hydration system and bottle cage (the square nut serves as a spacer for your other bottle bolt, so the cage is flush.
Once the thing is on, you can screw a CO2 vertically into the threaded hollow, on either end, holding two. The package comes with two mounts, so you can mount as many as four CO2s to a rear hydration system. Mark Vandermolen from Profile Design says you can mount them under your downtube bottle cage as well.
What does it mean? It means for my wife, as you can see in the picture of her bike, she can save space in her tool bag (which she puts in her rear cage on her HydroTail). For race day, she has them at hand, and now wrapped with electrical tape to a tubular tire, or a seatpost.
Erika Csomor, whom is staying here in San Diego and I passed one to, is jazzed, as she said she has typically put CO2s in her Bento Box on race day. Now she has more room for more important stuff in there, like food.
They're easy to access, easy to know how many you have for race day, and you don't need to wrap them to your frame with electrical tape.
Maybe some of you are rolling your eyes: "That's it?" If you race and see stuff littered across the race course, one of those things that causes massive fear of riding over is a CO2 cartridge. The more you can affix stuff to your bike without rudimentary methods, the better off we all are. And you look just a little more pro.
So there it is. It ain't a solution to our economic plunge, but it will make your training and racing a bit more organized. The less electrical tape on a bike, the better.
Thanks for all the great guesses, and thanks to Profile Design for sending me a prize for the giveaway. Maybe I'll do some more of these giveaways again.