Four months after Echostar’s (SATS) Sling Media demoed an application at Macworld 2009 that allowed Apple’s (AAPL) handheld mobile devices to pick up programming transmitted by a Slingbox, the long-awaited SlingPlayer Mobile for the iPhone went live overnight on the App Store. Price: $29.99.

Slingbox, for those who haven’t yet parted ways with their conventional TV sets, is a wireless streaming device that takes the signal from a cable, satellite or video recorder and puts it on the Internet, where it can be displayed by a computer with a broadband connection and a password unique to that particular box.

Sling players have been available for some time for a variety of mobile devices — including those running Nokia’s (NOK) Symbian, Research in Motion’s (RIMM) BlackBerry OS, Microsoft’s (MSFT) Windows Mobile and Palm (PALM) OS.

Now it’s available for the iPhone as well.

We downloaded a copy Wednesday morning and after some unpleasantness locating a 32-digit identification number we didn’t know we had, we found that it worked as advertised — at least over our Airport network.

Citing concerns about network congestion, AT&T (T) has restricted Slingbox use to Wi-Fi (see Engadget for the carrier’s official statement). But early reports suggest that jailbroken iPhones may be able to pick up a signal over 3G and EDGE as well.