The set overlap between "iPhone owners" and "fans of professional golf" isn't trivial, so it's worth mentioning that the free app for the 92nd PGA Championship is available in the App Store. You can follow along with the action at Whistling Straits this weekend in glorious Retina Display detail, and with a $1.99 in-app purchase you can get live video of marquee players through their entire rounds, or see the entire field play the course's par 3 holes. Of course, live coverage is also available at pga.com or on television.
Even without chipping in for the live streaming, there's plenty of video in the app: highlights, course overviews and instructional clips are all included gratis. The app includes customizable push notifications, so you can keep abreast of the latest news or zero in on particular players, round schedules or exceptional events (double bogeys, birdies/eagles, etc.).
If you like the PGA Championship app, there's more around the corner; the 2010 Ryder Cup App will be in the store in September.
Check out the gallery below for more views of the app.