The first of Apple's big iPhone OS 4 announcements was multitasking, and the first set of multitasking announcements were APIs to let streaming music (think internet radio), location services (think navigation, check-in games, social networks), and VoIP services (think internet telephony) register threads in the background. For users this means you can keep listening to your songs, getting your turn-by-turn directions, and answering your virtual phone all while surfing the web or playing a game.

To find out what it means for developers, we asked some. Read what they had to say after the break!

NAVIGON, which makes MobileNavigator [$79 -- iTunes link]:

We are very excited about the background location feature and will work on implementing this into our app, so that the app can run in the background and provide directions when, for example, taking a call. We’ve really been waiting for this, so it’s great to see this happening now.

TeleNav, which powers AT&T Navigator [Subscription - iTunes link], Rogers Navigator [Subscription - iTunes link] and other location-aware services and apps:

Overall, we are very excited about the new multitasking and background location features as it opens up a variety of new capabilities for navigation and other location-based services on the iPhone. We’re actively working on new features and capabilities and look forward to sharing these with consumers soon.

Slacker, which offers Slacker Radio [Subscription - iTunes link]:

Right now 4 out of 5 of our mobile apps are on platforms that support multitasking and our listeners have let us know they enjoy being able to utilize their smartphone's functions while listening to their favorite music. We are elated that soon Slacker listeners using their iPhone will have this same capability.

Fring, which makes the VoIP service of the same name [Free - iTunes link]

fring is congratulating Apple for reaching this decision, which will only enhance the iPhone/ iPad's user experience. With the allowance for VoIP calls over 3G and now the background VoIP functionality, Apple is taking great steps allowing for the freedom of choice fring has been a big supporter of, since day one.

Seems like they're happy. While some internet chatter has revolved around whether iPhone OS 4 is providing "true" multitasking or not, the end result for the user is that they're getting these 3 types of functionality in the next update. Of course, we'd enjoy other services as well, including persistent connections for SSH and like protocols, and background updates for timelines like IM, but from zero to this for 3rd parties is certainly a good start.

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