Apple App Store continues to show Xcode 4.1 "Installed" even though I have uninstalled it. Ok, so Xcode 4.1 was working fine and I did the incremental update to 4.1.1 at the App Store when it came out a few days ago.  Nothing has been stable since that update.

So I found on Stackoverflow to use the command:
      sudo /Developer/Library/uninstall-devtools --mode=all
in uninstall the environment.

It seemed to work as expected. After that, I deleted the remaining empty subfolders in the /Developer folder, emptied the Trash, and rebooted.  

At this point I have in every real sense uninstalled and revoved Xcode 4.1.x. So I go back to the App Store to re-download the full current 4.11 package.  Yes, I am on Lion. But the Xcode page in the App Store continues to state that I have the package INSTALLED ! And so, does not provide me the ability to re-download it.

Why will the App Store not permit the re-download of a free product in its entirety, as a registered Apple Developer, even if I did have it installed ?  Which I don't.

What to do ? Thank you, I am in a bind here. I need to affect some setting on my Mac that will not indicate a false-positive that I have Xcode installed.  Ideas ?

-Ric
Check your applications folder for the Xcode 4.1 application installer. This is what the Mac App Store actually downloads and is probably reported as installed. Run that again to reinstall.