Downloads from iTunes U have topped 300 million in three years, making it one of the world’s most popular online educational catalogs, Apple announced today.

iTunes U, which was launched in 2007, helps member institutions manage and distribute educational PDF, audio and video content for students.

The numbers Apple has cited for the service are impressive: Users have downloaded 300 million items from a catalog of more than 350,000 audio and video files, and more than 800 universities — including Stanford, Yale and MIT — distribute materials to students using the service.

As of 2 p.m. PT today, Facebook has opened its Places Read API for all developers.

The Read API will scrape Facebook’s data so your app can access a user’s checkins and his or her friends’ checkins, as well. You’ll be able to grab all checkins made with Places and Places-enabled applications. Facebook is hoping the apps created or augmented with this API will enhance real-world social experiences such as going to a concert, attending a conference or traveling on vacation.

You can also get checkin data from specific Places and Pages.

Most devs won’t yet have access to the Write and Search APIs; Facebook is only making those available to select partners in a private beta. For example, Yelp, Gowalla and Foursquare will be able to push their checkins to Facebook Places, allowing users to simultaneously checkin to their services as well as Facebook’s.