Yes, you can install Xcode 3 on Lion. I am living proof that it works.
BUT (there’s always a but ) if you do you will not be able to validate and upload apps to the mac app store using Xcode 4, even if you install it after. This is something I have discovered after hours of excahnge with developer support.
There is reasons why you can’t have Xcode 3 on Lion, and this is one of them.
Just something I thought anyone reading this should be aware of.
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