Starting today, the first class session of 10 weeks is available for free download at iTunes U, a dedicated area within the iTunes Store .The iPhone Apps popular that it became a class at Stanford for the winter semester.

Users of the iTunes Store may subscribe to and download each week’s lecture videos and accompanying materials for the 10-week course, iPhone App Development, which is taught by Apple engineers. However, grades, college credits and access to classrooms and teachers are limited only to Stanford students.

“We have a large enrollment; we’re going to be oversubscribed again,” said Julie Zelenski, a professor of computer science at Stanford, who helps coordinate the class.

“We anticipate that it will be just as wildly popular off-campus, like last year when the course has been downloaded 4.4 million times on iTunes U,” said Brent Izutsu, Stanford’s project manager for Stanford on iTunes U.

This year’s course will teach iPhone OS 3.1, the latest operating system for the iPhone and iPod touch, released last summer. “The curriculum has been upgrade to take advantage of new opportunities and capabilities in iPhone OS 3.1,” said Izutsu.

Apps are small downloadable software programs that allow cell phone users to play games, get directions, balance their checkbook, fine friends and perform thousands of other tasks, both recreational and utilitarian.

Some of the apps created by students in previous classes are available at Apple’s App Store, which offers more than 100,000 apps. More than 3 billion have been downloaded apps, ranging from games to location based social networking and productivity tools.

This year, the course videos have a new feature. “We are getting the videos closed captioned this time, if they will be even more accessible,” said Zelenski. Besides to helping those with hearing disabilities, the captions will be useful to English language learners or students trying to understand the more technical aspects of the classes, she said.