Today marks the start of Apple's (NASDAQ:AAPL) Worldwide Developers Conference, where the company is expected to announce the new features of its iOS 6 operating system as well as new laptops. Specifically, Apple is expected to announce a new version of its mapping program for iOS that does not rely on information from Google Maps. The company is also expected to announce system wide support for Facebook, much as it has already done with Twitter. Interestingly, according to Nielsen, Facebook is the most used app among iPhone owners, followed closely by Maps. Apple's news should draw widespread attention; according to research firm Nielsen, Apple is the top smartphone manufacturer in the United States, with about 1 in 3 smartphone owners using iPhones in March 2012. Apple's keynote presentation begins at 1 p.m. Eastern today. Fierce will be covering all the major news from the event. Click here for all the headlines from Apple's WWDC.