Here's something I've been wondering about. Ever since Apple released the roadmap of iPhone development and the SDK details, they mentioned that third-party apps can't run in the background. After avoiding it for months, I finally did the jailbreak on my iPhone last month because I realized I listened to music/podcasts constantly on the device, and none of that data was reaching my last.fm account. I opened up my iPhone to third-party apps just to get MobileScrobbler running, and it works great.
But it does the magic in the background (even over EDGE, which I optionally allowed). You play songs as normal, and every so often a tiny ping goes out to last.fm, logging the music played. I imagine that won't be possible with the official SDK but I haven't seen anyone mention this app specifically.
So mac/iPhone nerds: will I have to keep a jailbroken out-of-date iPhone to keep using MobileScrobbler come June when the new iPhone stuff is released?