• by Erik Sass  @eriksass1, April 21, 2010

The huge number of iPads sold in the first week of availability -- about 500,000 units -- foreshadows a similar feeding frenzy for iPad apps over the coming weeks and months, according to Macworld.com, which reported early projections based on the first sales figures from popular app makers.

Publishers were ready with apps for the new tablet-style computer even before the iPad went on sale. Many believe the device will be a lifeline to beleaguered magazine and newspapers.

Some of the projections come from Vimov, a company that sells a weather app called Weather HD priced at $1. Vimov compared the initial sales figures for iPad app downloads with earlier sales figures for iPhone apps. It estimates that altogether, the top 1,000 apps downloaded by iPad owners are set to earn approximately $136 million per year in the first year of business -- and that's just based on U.S. sales.

Once the iPad hits international markets, Vimov estimates iPad app sales could double to $272 million.

Looking ahead, Vimov says iPad apps could match iPhone apps, which increased from 100 million downloads two months after launch to 4 billion downloads 21 months after launch. At that rate, Vimov calculates iPad app sales could be a $1 billion per year business just two years from now.

Following months of rumors and speculation, the debut of the iPad on April 1 triggered a rush on stores with scenes familiar from previous much-hyped Apple product launches.

Last week, Zinio, which creates digital versions of magazines for print publishers, revealed that its Magazine Newsstand and Reader is the No. 1 free news app downloaded by new iPad owners. Even more noteworthy, the same Zinio app held fifth place overall in free iPad apps, behind No. 4 Netflix and ahead of No. 6 The Weather Channel.