Following increasing competition, most recently from SmugMug’s nifty Camera Awesome app, everyone’s favorite iPhone camera replacement app Camera+ is rolling out a major update today. There are a ton of new features in version 3.0 of the app, including speed improvements, multiple photo import, better sharing options, and more, but the biggest change isn’t really a consumer-facing feature at all – it’s an API.

Starting today, developers can integrate Camera+ into other apps or create web services that make use of the photos shared by the app’s millions of users. According to Camera+’s maker, Lisa Bettany, several developers are already integrating Camera+ into their apps using the new APIs, including WordPress, Tweetbot, Twitterific, Foodspotting and Twitterlator Neue.

For those unfamiliar (Android users?), Camera+ is the 10th best-selling paid iPhone app of all-time, and it recently shipped its 7 millionth copy. The app serves to replace the iPhone’s built-in camera with…