Yeah, since iOS4, any app can run in the background for 10 minutes. Certain apps may be approved to run in the background longer. It's covered in the iOS App Programming Guide.

Here's a link to the pdf (you might need a developer account to access): http://developer.apple.com/library/ios/documentation/iphone/...

If you can't or don't want to access the pdf, here's a link to a SO answer I gave on the subject: http://stackoverflow.com/a/9738707/239074