Is there a way to un-update an app?

You don't roll back.
Have you tried other trouble shooting steps first?

Reboot
Reset
Restore

Reset is the most common fix and only takes a min. Hold BOTH the HOME and LOCK buttons. DO NOT let go when it says slide to turn off but keep holding. Let go once the screen comes back up with the Apple Logo.

What the **** is the point of updating something if it's going to make it non-usable?!

I'm sure that was intended by the developer... it's really good for business.

If you have not backup/sync your iphone yet after you updated, go to your itune's folder and look for that app. Copy that app to another location. Then delete your app from your iphone and sync. Copy your app back into your itune's folder and sync again. Make sure your app is checked in the app tab. I am assuming you backuped your iphone after you loaded your previous version.

If a reset does not fix your issue you may need to restore your iPhone and load the app again.

Before doing a restore though I would go to the developer's website and see if there are other reports about problems with the upgrade. On one of mine there was a posting from the developer that there was an issue and it would be fixed in the next upgrade which appeared shortly after that.

It obviously had nothing to do with your first question. It was to point out the absurdity of your second.

Frustration understood and we see vents here all the time, useless as they are. Never mind on the rest - my original post was somewhat tongue-in-cheek.

If you haven't yet emptied your Trash, you will find the old version of the app in there. It was moved out of your /Users/<your_name>/Music/iTunes/Mobile Applications/ folder during the update and replaced with the newer version. Just drag the old version back into the Mobile Applications folder and remove the new version. Next time you sync through iTunes, the old version should be put back on your iPhone.

I successfully did this when an app update made it iOS4-only.... I rolled back to the previous version that was still 3.1.3 compatible.

Hope this helps.

Rob

But won't deleting the app from the device cause you to lose any app files and data? Is there any way to go back to an earlier version but keep your valuable data?