According to Broadpoint analyst Brian Marshall, the sale of applications, e-books, newspapers and magazines for the iPad is predicted to equal nearly 30% of the revenue Apple will earn from selling the hardware by the end of 2011.

In a note to clients — as noted by “AppleInsider” (http://www.appleinsider.com), the analyst believes content revenue will top 10 percent of total iPad hardware revenue by December of 2010, and a year later that number will nearly triple. He’s increased his forecast for iPad shipments in the 2010 calendar year to four million units, up from a previous prediction of 2.2 million.

Marshall told clients that “if the device lives up to its potential,” he could see it shipping more than seven million in this year alone. “We believe the iPad offers a rich media experience that will translate into a content-based recurring revenue stream over time,” he says.

Saturday, April 3 is when the iPad will go on sale in the U.S. At least the Wi-Fi only version will; the Wi-Fi + 3G model will hit US store sleeves in late April.

In addition, all models of iPad will be available in Australia, Canada, France, Germany, Italy, Japan, Spain, Switzerland and the UK in late April. Beginning a week from today, on March 12, US customers can pre-order both Wi-Fi and Wi-Fi + 3G models from Apple’s online store (http://www.apple.com) or reserve a Wi-Fi model to pick up on Saturday, April 3, at an Apple retail store.

The Wi-Fi iPad will set for a suggested retail price of US$499 for 16GB, $599 for 32GB, $699 for 64GB models. The Wi-Fi + 3G models will be available in late April for a suggested retail price of $629 for 16GB, $729 for 32GB and $829 for 64GB. iPad will be sold in the US through the Apple Store, Apple’s retail stores and select Apple Authorized Resellers.