Code signing can be a pain, but the fact that Xcode gives very little information about a mobile provisioning file does not ease things.
Let me introduce a new QuickLook plugin. This plugin allows you to get a QuickLook preview for all .mobileprovision files.
It gives you the name of the profile, its creation and expiration date, its App ID, and a sorted list of all the UDIDs included.
More information can be found here: http://www.macmation.com/blog/2011/10/quicklook-plugin-for-mobile-provision-files/