So, I basically developed and tested my app using a developer provisioning profile.
now i'm almost ready to submit my app to the app-store, and I was going to use the app-store provisioning profile. so I don't really need to mess with the ad-hoc one at all right?
(I think it's some kind of voodoo magic for multiple developers or something?)
thanks
Ad-Hoc distribution is outside the App Store. You must sign your app with the Provisioning Profile approved for Distribution and for you app. That is to say if you are specifying an App ID. That latter is common if you are doing Push Notifications or In App Purchases.
You only need ad-hoc if you want to test further with others. It is basically the same as the final approval provisioning. You have up to 100 users that can install your app.
Ad-hoc provisioning helps you test at a larger scale than your single developer test.
Testers will always find a way to break your app, so it is a good practice to use this step to help reduce your bug count and smooth your approval process.
As Jason said, you will need to go through the provisioning process in order to submit your app to the App Store. It can be a tedious process the first time - but you can't avoid it.
That said, Distribution builds (non-Debug builds) are different executables. So, it makes sense to test them as such. It is unlikely that problems that were absent in the Debug build will suddenly manifest themselves in the Distribution build - but it's possible.
Also, unless you have at your disposal every iDevice with every combination of iOS releases that you are targeting, then it's nice to have others help make sure that there are no gotchas.
Bottom line: I wouldn't consider submitting an app to the App Store without first deploying Ad Hoc an build on all my devices and sharing it with a few other iDevice users. But, YMMV.