Some food for thought: Popular Science magazine, one of the first magazines in the world to offer subscriptions for iPad on iTunes, sold its 10,000th subscription for its iPad edition almost six weeks after accepting Apple's online publishing payment system. This is just a small amount compared to 1.2 million subscribers of the print model, but a big number when compared to other iPad magazine initiatives.

“We are very excited,” Gregg Hano, vice president-group publisher for Bonnier Technology Group, which publishes Popular Science, told Advertising Age. “We really did not have any expectation of what would happen, because we’re really pioneers.”

In the beginning of last year, many editors said the iPad test would not start until they could offer subscriptions. Then, when Apple finally introduced a subscription system last month, many publishers were disappointed. After all, publishers will know nothing about their own subscribers on App Store. Apple says that unless subscribers explicitly allow them to share their information, they will not share it with the publishers. The majority of publishers want a direct connection with their readers for commercial reasons.

But Popular Science took the risk, accepting Apple’s system. They ended up doing the right thing. Now “Pop Sci” has more than 10,000 iPad subscribers, each one paying US$14.99 per year — a little more expensive than the print subscription of US$12.99 available on its Web site. The magazine also sold around 2,500 single copies of the March edition on iPad for US$4.99, the same price of the print version.

“We’ve been averaging 10,000 to 12,000 unit sales per month almost since the beginning,” Hano said. “Now we’re going to be above that in March. We’re inching up over that. And we look forward to continuing to see subscriptions grow. Hopefully people keep testing Popular Science on their tablets, and then hopefully come back and subscribe.”

We don’t know if they are charging more for the iPad subscription to help pay for the iTunes share (30%), but it shows some real results to help us think more about the model.

One thing is for sure: “Pop Sci” didn’t wait, and now they have more information about selling content for tablets.

Let’s keep an eye on their numbers.