You need a version of Xcode < 3 apparently.
And I was about to grab the source and try and get up to date a bit too!
Ironically I only updated XCode last night. Although it was already on v3 anyway, just not the latest.
[EDIT]PS: Cheers Dave & Zuki. Nice to see the project not die entirely. I just hope you don't get bombarded with too many 'X game don't work' questions