Investing millions to launch an iPad-only publication may prove to be one of the best ways of making a small fortune from a large fortune, but for traditional publishers that have been hawking their wares on the iPad, Kindle and NOOK, tablets are starting to have an impact.

That’s according to two executives from Condé Nast and Hearst who took part in a panel at the American Magazine Conference.

Both indicated that their companies are close to achieving $10m in revenue from tablets.

Hearst is currently seeing 300,000 paid downloads of its content each month from tablets, and “that number is going to double for us in short order” according to Hearst Magazines president David Carey.

Condé Nast is also looking at eight-figure numbers: it anticipates $15m in revenue by the end of this calendar year from paid tablet content and advertising.

As John Koblin of Women’s Wear Daily (WWD) notes, “when Apple’s iOS 5 system debuts next week, publishers hope that the Newsstand app will provide a bigger boost to single-copy sales and subscriptions, by providing an easier way to search for titles and organize them“.

But when it comes to tablet publishing, it’s not all about the iPad. Indeed, Android-based devices that are part e-reader, part pure tablet are increasingly important to publishers.

Case in point: Hearst’s Carey told WWD that his company’s ability to double its tablet subscriber base “will depend in large part on Kindle Fire and Nook Color sales during the holiday season“.

He described Hearst’s early adoption of the NOOK Color as “a fantastic opportunity for us,” and the company may find the Kindle Fire to be an even bigger opportunity.

If the leaks about Kindle Fire pre-sales are accurate, the $199 Android-based device may become the fastest-selling tablet ever, beating out even the iPad.

Of course, the revenue publishers are seeing from tablet sales won’t necessarily equal profit. Many traditional publishers still face considerable challenges in building business models for the digital age.

But one thing is increasingly clear: the business models that aren’t based around one channel or one platform are proving to be the most fruitful. The iPad may
be the tablet device to beat, but publishers capitalizing the most on the tablet
opportunity aren’t treating the iPad like the only game in town.