xcode 3.2.3 installation failed on Mac 10.6.3
It seems the error stems from an expired certificate covering the iOS portion of the package. I assume you only need 3.2.6 to build universal binaries that support older PPC as well as Intel Macs right? That being the case, you can simply decline the second licence agreement covering iOS. The installer should then proceed to install only the Mac-related tools and SDKs.
Update: I see you were referring to 3.2.3 while I was referring to 3.2.6. I am not certain the installer works the same way, but imagine you would want 3.2.6 anyway?