I learned a little bit of information today. Apple has changed the policy on provisioning profiles expiration. Instead of expiring after one full year the expiration now happens in the year 2079. I think this is good since you would not want to create a new provisioning profile every year. Whatever triggered this change (the new iCloud?, iOS5) must be something that is coming soon to the iOS universe.
What is a provisioning profile?
A Provisioning Profile is a collection of digital entities that uniquely ties developers and devices to an authorized iOS Development Team and enables a device to be used for testing. A team can be just a one man team or several developers and QA testers. A Development Provisioning Profile must be installed on each device on which you wish to run your application code. Each Development Provisioning Profile will contain a set of iOS Development Certificates, Unique Device Identifiers and an App ID. When a user downloads and installs an app from the AppStore iOS does this automatically for them. But if you distribute apps ad hoc the profile must be installed manually.
Devices specified within the provisioning profile can be used for testing only by those individuals whose iOS Development Certificates are included in the profile. A single device can contain multiple provisioning profiles.