- Dropbox: Everyone's favorite file-syncing tool can now sync and complete uploads in the background, and also adds in support for fast app switching.
- Evernote: the notes-in-the-cloud app adds support for fast app switching, and can continue to record audio notes in the background.
- Pandora: Yes, you can finally play Pandora in the background -- and the quick music controls on the left-most panel of the app switcher even control playback when it's in the background. Nifty.
- New York Times: Nothing major, but the Gray Lady supports fast app switching, so you can jump right back into an article without reloading.
- ESPN ScoreCenter: Supports fast app switching, although you'll still have to open it up for scores to refresh, since there's no background updating API.
- How to Cook Everything: Funny that a cookbook is one of the first iOS4 apps out there, but we're Mark Bittman fans, so this is pretty cool -- it supports fast app switching, so you don't have to reload a recipe every time you close the app. Oh, and it's got newer high-res art for the iPhone 4. Tasty.
- Fandango: Now has fast app switching, so you can juggle other tasks while buying your movie tickets.
- LinkedIn: Yep, LinkedIn's iPhone app adds fast app switching to the mix.
Update: We're listing off more as we find them after the break -- check it!
Update 2: "Tested for iOS4" doesn't guarantee new features, but if you want to know which apps can make that claim, here's a handy Google search. [Thanks, jihuiwen!]
- Tweetaholic: This Twitter app supports fast app switching, and can also refresh your timeline in the background.
- Ego: This stats app can tell you everything from how many Twitter followers you have to how many people have subscribed to your site's RSS feeds.
- National Rail: Britain's National Rail app now supports fast app switching. [Thanks, QwaF.]
- Ambiance: This "environment enhancer" has been totally rewritten for iOS 4, and can now play ambient audio, like thunderstorms, in the background. [Thanks, jdwusami]
- Windows Live Messenger for iPhone is now out -- that's new for iOS 4.
- TuneIn Radio is now ready to play background audio, and support fast app switching.
- Wordpress for iPhone is now iOS 4-ready as well.
- Facebook has been updated with the ability to watch videos, 720p picture uploads, and the ability to view and write on walls of events. Fast app switching doesn't appear to have made the cut, though.
- Rockz has iOS 4 support now, one of the first games we've seen to add it.
- Colloquy has been updated for iOS 4, which has the Engadget staff all a-flutter. It uses an interesting trick to keep your IRC session open in the background -- it sets a 10 minute task completion timer, and when it runs out it disconnects. Switching back to the app resets the timer, though, so if you're flipping back and forth it's virtually infinite.
- Tasker now utilizes local push notification for scheduled tasks and keeps track of your location in the background to alert you of nearby tasks. The graphics have all be upped for the retina display.
- Pianist now has high-res textures.
- Motionx GPS now has background tracking and fast app switching. [Thanks, Dennis H.]
- Black Book and Pink Book have been graced with high-res graphics and in-app SMS capabilities. Be also on the look out for free, iAd-supported versions soon.
- Toobz now supports fast app switching.
- Twitter: The official Twitter Inc. app now supports fast app switching and sending tweets when switched to the background.
Apple iPhone 6