This is a legit story. That being said, the story is based upon quotes from the CEO of SlingMedia. He's love to add support for the iPhone because it would help drive sales of the SlingBox. As for HSDPA, Gizmodo and others have reported that a
3G iPhone was "in the works". I've also read a number of places where it was said the iPhone "could" support 3G. My thinking is they announced the iPhone in January. At that time, they gave an overview of the specs. I wouldn't surprised in the least if Steve Jobs announced a few new things when it is released. If it does release with EDGE support, then I'd doubt you'll see SlingBox support. SlingBox works great with EVDO (and it's safe to assume HSDPA), but I question the quality of the experience on EDGE. I've used MobiTV with EDGE and it suffered from buffering issues. SlingBox would most likely have the same issues (as evidenced by their lack of support for the Treo 680).
-Chris