One more tidbit worth pulling out from today’s WWDCannouncements: Netflix will bring a streaming video app to Apple’s iPhone and iPod touch this summer. The company was quick to clarify two important points right out of the gate: The app is free, and it works over AT&T’s mobile 3G network, not just WiFi.

That last point is a small surprise, given that AT&T just discontinued its unlimited 3G data plan for new customers. Existing iPhone and iPad customers can keep their old arrangements, but anyone who’s signing a fresh contract will be limited to either 200 MB of 2 GB per month, depending on the plan.

If you’re planning on doing a lot of 3G Netflix streaming, you’ll want to stay on that unlimited plan since videos use up a lot of bandwidth.

Netflix CEO Reed Hastings announced the app on stage Apple’s WWDC conference alongside the new iPhone 4, but he wasn’t on stage long enough to go into detail about the app’s features. He did say that Netflix for iPhone will pick up where you left off in movies or shows you’ve already started watching — even on other devices. Also, the app uses “adaptive bitrate technology” to maintain its connection when you move between networks.

This app already seemed like a sure thing months ago when Netflix sent out a customer survey gauging interest in an iPhone or iPod touch version some time before Netflix for iPad launched