Lonely Planet launched five Android travel guide apps for U.S. cities, incorporating augmented reality technology from the Wikitude app, in beta in October. Now the publisher is debuting more apps, on a public basis, for half of the 50-plus main city destinations it covers.

“This is a way of us testing the Android Marketplace,” Lonely Planet’s innovation ecosystems manager Matthew Cashmore tells paidContent:UK. “There is potential here. We have 25 guides —if things go well, we will roll out the rest.”

Guides are priced at $4.99, in dollars even in non-U.S. markets, because it is onerous to deduct tax from Android Marketplace downloads outside of America, Cashmore said. Lonely Planet is doing a revenue share from app revenue with Wikitude app developer Mobilizy.

The Android betas have shifted an average 1,000 a week with no search listings or marketing push. “It’s getting to the point where there are more Android devices out there than iPhones—that’s not a bad thing,” Cashmore added.

Though this is BBC Worldwide-owned Lonely Planet’s first full Android foray, it already published iPhone city guide apps, and recently reported a 500 percent sales uplift from a promotion coinciding with the Icelandic volcano eruption, in which it made some editions free and halved the price of others…

“We got three million downloads in 24 hours across the apps we gave for free,” Cashmore said. “And the halo effect in to the paid apps was absolutely phenomenal—our paid downloads went through the roof.

“We get a subsequent spike whenever our apps are featured in ads or we add new features. But this was the biggest spike we’ve ever seen—and the drop-off has been much slower.”

But the iPhone versions are not yet slated to get augmented reality features.

Cashmore says his strategic watchwords are “relevant ubiquity” - using mobile to make pertinent information available to travelers, in whatever context they may be.

On Tuesday, Lonely Planet debuted iPad versions of its Discover e-books, bearing hypertextual navigation between page sections, maps with clickable points of interest and a price of $17.99/£12.99/€11.99 after an opening promotion.

It’s the e-books which are more geared toward pre-travel or leisurely research, while the mobile apps are designed to give travelers on-the-spot info.

“We can make it look really nice (on iPad) - which we’ve been unable to do on the Kindle,” Cashmore said. “We’ve been able to replicate the book experience for the first time, which we’ve not been able to do on other e-readers.”

In the coming weeks, Lonely Planet will release $2.99 Android versions of the phrasebooks already available on iPhone.

Lonely Planet 2009/10 profit was up by £5.1 million to £1.9 million, on 19.5 percent higher sales of £51.4 million.