I just got a new iPhone 4 with iOS4...and it supports background location updates! I've decided to bring MoosTrax back to the iPhone. I'm looking for beta testers...and then soon I'll be pushing it to the App Store.
Applying for the beta
Please e-mail email@example.com with your iPhone’s UDID.
For information on finding the UDID, go here: http://www.geekology.co.za/blog/2009/07/how-to-check-your-iphones-udid-from-itunes/