Where can I download old iOS versions from Apple? I need to test my app with older version of iOS and can't find exactly where to download them from Apple.

Anybody know the adress?
As far as I'm aware Apple doesn't offer the links directly, but iClarified has a complete list of iOS downloads for all models of iPhone available here. It came in handy when I downgraded my old 3G back down to 3.1.3