PBS released an iPad app last October with access to videos and information about the donation-supported network's programming. Now, the network has done the same for the iPhone and iPod touch, with a free app simply called PBS. Just like the iPad app, you can watch clips and full-length episodes of some of the network's most popular programs, as well as see schedules for both national and local PBS programming. The iPhone app also lets you set reminders for certain programs, and you can also share videos with friends on Facebook and Twitter, or through email.
I'm personally a big fan of shows like Antiques Roadshow and Nova, and having them available to watch anytime on the iPhone is great. The app is completely free and available for download right now, but if you like it, do look into hooking up your local PBS station with a nice donation.