CEO Steve Jobs said Apple has been "working hard" to get iPads into the hands of even more people around the world, "including those in nine more countries next month." In response, analysts at Piper Jaffray said they believe the iPad is a long-term investable theme and a reason to buy shares of Apple.

"We also believe investors are underappreciating the global opportunity of the iPad as the 'Mac for the masses,'" Piper analysts Gene Munster, Michael Olson, and Andrew Murphy wrote in a report released Tuesday. "Given these strong results, we are raising our calendar year 2010 iPad unit estimate from 6.2 million to 7.5 million."

Not Just About Hardware

Apple's latest marketing success story isn't just about the hardware. Earlier this month, Jobs told attendees at the Apple Worldwide Developers Conference that five million e-books were downloaded by iPad users in the first 65 days, which he estimated was equivalent to about 22 percent of all e-book sales.

Gartner Research Vice President Allen Weiner noted that this could be an indication that consumers are content with reading e-books on an LCD screen even though it's harder on the eyes than on dedicated e-paper devices such as the Kindle, nook and Sony Reader.

"The takeaway is that Apple is selling lots of e-books for the iPad," Weiner wrote in a blog. "This early in the e-reader evolution, perhaps consumers are willing to trade a less-optimal e-reading experience for the added bonus of video, games and other applications available for the iPad."

A Compelling Professional Device

According to Apple, developers have already created more than 11,000 new apps for the iPad, many of which take full advantage of the device's multi-touch user interface, large screen, and high-quality graphics. The iPad also is capable of running almost all of the more than 225,000 apps in the App Store, including those for the iPhone or iPod touch.

One reason why the iPad is striking such a harmonious chord with users is that it is capable of performing many tasks well -- from browsing the web, sending e-mail and sharing photos, to watching HD videos, listening to music, and playing games -- despite its diminutive size and weight. However, the bigger surprise for many users is how well the iPad performs business tasks.

Gartner analyst Andrea Di Maio initially thought he would use the iPad mostly as a home device -- reserving its portable use for enjoying videos on long trips -- but now he admits he was wrong. "What the iPad has turned into is a compelling professional device," Di Maio wrote in a blog. "I use it to take notes during meetings, to show slides to small groups around the table, as well as to do formal presentations."

Still, Di Maio noted that the iPad isn't the perfect business tool. "Compatibility between Keynote and PowerPoint is not perfect, in particular when it comes to animations and the use of shapes containing text," he wrote. "Another downside is the inability to transfer notes or presentations unless there is a wireless connection."