I get it too. I'm just updating to lion p2r2, and will install Xcode 4.1 Developer Preview 4.
Have you had any luck? The only thing I'm going to vary from the normal build instructions is to specify 64 bit as per * Under Mac OS X 10.6 and later, `configure' by default selects 32-bit mode for building Racket. To build Racket in 64-bit mode, use `--enable-mac64'. Cheers, Stephen ;; Process: DrRacket [95500] Path: /Users/USER/*/DrRacket.app/Contents/MacOS/DrRacket Identifier: org.racket-lang.DrRacket Version: 5.1.1 (5.1.1) Code Type: X86 (Native) Parent Process: launchd [304] Date/Time: 2011-05-07 20:48:16.203 +0100 OS Version: Mac OS X Server 10.7 (11A390) Report Version: 8 ;; _________________________________________________ For list-related administrative tasks: http://lists.racket-lang.org/listinfo/dev