The previously jailbreak-only Simplify Media has just hit the iTunes App Store, allowing you to stream your entire iTunes music library (plus up to 30 of your friends') to your iPhone. The official app has all the features of the old version, including album art, lyrics and artist bios, plus works over EDGE, 3G and Wi-FI. It's free for the first 100k downloaders, so we can't think of any reason why you wouldn't want to use this seeing as it gives your phone an essentially unlimited amount of storage space. Video demo after the jump.
[Apple]
DISCUSSION
The link works fine. I just wasn't browsing Giz on my phone, and I'm at work so I don't sync my phone here. So I copied the link, pushed it to my iPhone, and it worked there.
It's just not working through the app store on the iPhone, when you search it shows up but then says No Matches when you click on it.