Had to do look it up. I think they meant built including GCC 4.0 and not built using 4.0. Apple, in this article says this about it.
The compiler version matters because changes to the Application Binary Interface since Mac OS X v10.0 have rendered C++ and Objective-C++ executables incompatible with earlier releases. However, C and Objective-C programs still run the same. To build for 10.1 and earlier you must use version 2 of GCC for C++/Obj-C++ applications and kernel extensions; version 2.95.2 was the GCC final release that shipped with Mac OS X v10.1. GCC version 3.1 shipped with Mac OS X v10.2 Jaguar, and 3.3 with Mac OS X v10.3 Panther. Note that if you mix languages in the application you should rebuild using the appropriate compiler version: 2.95.2 for Mac OS X v10.0 and v10.1, 3.1 for v10.2 Jaguar, and 3.3 for v10.3 Panther.
Addendum:
Further research turned up a more direct reference.
Along with improvements to the GUI, Xcode 2.0 will ship with GCC 4.0 which features a new C++ Parser and several code generation improvements including auto-vectorization. While hand-tuning Velocity Engine code can get you the maximum performance from the G4 and G5 processors, now you can have GCC do the heavy lifting for you. You'll benefit from this without any extra effort, with auto-vectorization in GCC bringing anywhere between a 4X and 14X performance improvement to code that works with arrays of data.
Note, the article specifically refers only to the XCode toolset. Although I guess we can't infer from that anything about how the binaries were built.
s//----->\t/;$~="JAPH";s//\r<$~~/;{s|~$~-|-~$~|||s
|-$~~|$~~-|||s,<$~~,<~$~,,s,~$~>,$~~>,,
$|=1,select$,,$,,$,,1e-1;print;redo}
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OK, thanks for the details.
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