Fails to build in xcode 4.1/Lion

[Murf]

Title says it all.
The first error is simply that it wont build:

The run destination My Mac 64-bit is not valid for Running the scheme 'MGTwitterEngine'.
The scheme 'MGTwitterEngine' contains no buildables that can be built for the SDKs supported by the run destination My Mac 64-bit. Make sure your targets all specify SDKs that are supported by this version of Xcode.

When I modernize the project, and set target to 10.7 I get this:

Build target MGTwitterEngine

ProcessInfoPlistFile /Users/murf/Library/Developer/Xcode/DerivedData/MGTwitterEngine-eulwqzvrbtommlghsveeumzifrct/Build/Products/Debug/MGTwitterEngine.app/Contents/Info.plist Info.plist
cd /Users/murf/Downloads/mattgemmell-MGTwitterEngine-e40658f
builtin-infoPlistUtility Info.plist -genpkginfo /Users/murf/Library/Developer/Xcode/DerivedData/MGTwitterEngine-eulwqzvrbtommlghsveeumzifrct/Build/Products/Debug/MGTwitterEngine.app/Contents/PkgInfo -expandbuildsettings -platform macosx -o /Users/murf/Library/Developer/Xcode/DerivedData/MGTwitterEngine-eulwqzvrbtommlghsveeumzifrct/Build/Products/Debug/MGTwitterEngine.app/Contents/Info.plist

CompileC /Users/murf/Library/Developer/Xcode/DerivedData/MGTwitterEngine-eulwqzvrbtommlghsveeumzifrct/Build/Intermediates/MGTwitterEngine.build/Debug/MGTwitterEngine.build/Objects-normal/x86_64/NSURL+Base.o OAuthConsumer/Categories/NSURL+Base.m normal x86_64 objective-c com.apple.compilers.llvmgcc42
cd /Users/murf/Downloads/mattgemmell-MGTwitterEngine-e40658f
setenv LANG en_US.US-ASCII
/Developer/usr/bin/llvm-gcc-4.2 -x objective-c -arch x86_64 -fmessage-length=0 -pipe -Wno-trigraphs -fpascal-strings -O0 -Wreturn-type -Wunused-variable -isysroot /Developer/SDKs/MacOSX10.7.sdk -fasm-blocks -mmacosx-version-min=10.7 -gdwarf-2 -fvisibility=hidden -I/Users/murf/Library/Developer/Xcode/DerivedData/MGTwitterEngine-eulwqzvrbtommlghsveeumzifrct/Build/Intermediates/MGTwitterEngine.build/Debug/MGTwitterEngine.build/MGTwitterEngine.hmap -I/Users/murf/Library/Developer/Xcode/DerivedData/MGTwitterEngine-eulwqzvrbtommlghsveeumzifrct/Build/Products/Debug/include -I/Developer/SDKs/MacOSX10.7.sdk/usr/include/libxml2 -I/Users/murf/Downloads/mattgemmell-MGTwitterEngine-e40658f/yajl/build/yajl-1.0.7/include/yajl -I/Users/murf/Library/Developer/Xcode/DerivedData/MGTwitterEngine-eulwqzvrbtommlghsveeumzifrct/Build/Intermediates/MGTwitterEngine.build/Debug/MGTwitterEngine.build/DerivedSources/x86_64 -I/Users/murf/Library/Developer/Xcode/DerivedData/MGTwitterEngine-eulwqzvrbtommlghsveeumzifrct/Build/Intermediates/MGTwitterEngine.build/Debug/MGTwitterEngine.build/DerivedSources -F/Users/murf/Library/Developer/Xcode/DerivedData/MGTwitterEngine-eulwqzvrbtommlghsveeumzifrct/Build/Products/Debug -DDEBUG -include /Users/murf/Library/Developer/Xcode/DerivedData/MGTwitterEngine-eulwqzvrbtommlghsveeumzifrct/Build/PrecompiledHeaders/MGTwitterEngine_Prefix-domzcusankbpdrcyelqtaigpwofq/MGTwitterEngine_Prefix.pch -c /Users/murf/Downloads/mattgemmell-MGTwitterEngine-e40658f/OAuthConsumer/Categories/NSURL+Base.m -o /Users/murf/Library/Developer/Xcode/DerivedData/MGTwitterEngine-eulwqzvrbtommlghsveeumzifrct/Build/Intermediates/MGTwitterEngine.build/Debug/MGTwitterEngine.build/Objects-normal/x86_64/NSURL+Base.o

Command /Developer/usr/bin/llvm-gcc-4.2 failed with exit code 1

CompileC /Users/murf/Library/Developer/Xcode/DerivedData/MGTwitterEngine-eulwqzvrbtommlghsveeumzifrct/Build/Intermediates/MGTwitterEngine.build/Debug/MGTwitterEngine.build/Objects-normal/x86_64/CJSONScanner.o TouchJSON/Source/JSON/CJSONScanner.m normal x86_64 objective-c com.apple.compilers.llvmgcc42
cd /Users/murf/Downloads/mattgemmell-MGTwitterEngine-e40658f
setenv LANG en_US.US-ASCII
/Developer/usr/bin/llvm-gcc-4.2 -x objective-c -arch x86_64 -fmessage-length=0 -pipe -Wno-trigraphs -fpascal-strings -O0 -Wreturn-type -Wunused-variable -isysroot /Developer/SDKs/MacOSX10.7.sdk -fasm-blocks -mmacosx-version-min=10.7 -gdwarf-2 -fvisibility=hidden -I/Users/murf/Library/Developer/Xcode/DerivedData/MGTwitterEngine-eulwqzvrbtommlghsveeumzifrct/Build/Intermediates/MGTwitterEngine.build/Debug/MGTwitterEngine.build/MGTwitterEngine.hmap -I/Users/murf/Library/Developer/Xcode/DerivedData/MGTwitterEngine-eulwqzvrbtommlghsveeumzifrct/Build/Products/Debug/include -I/Developer/SDKs/MacOSX10.7.sdk/usr/include/libxml2 -I/Users/murf/Downloads/mattgemmell-MGTwitterEngine-e40658f/yajl/build/yajl-1.0.7/include/yajl -I/Users/murf/Library/Developer/Xcode/DerivedData/MGTwitterEngine-eulwqzvrbtommlghsveeumzifrct/Build/Intermediates/MGTwitterEngine.build/Debug/MGTwitterEngine.build/DerivedSources/x86_64 -I/Users/murf/Library/Developer/Xcode/DerivedData/MGTwitterEngine-eulwqzvrbtommlghsveeumzifrct/Build/Intermediates/MGTwitterEngine.build/Debug/MGTwitterEngine.build/DerivedSources -F/Users/murf/Library/Developer/Xcode/DerivedData/MGTwitterEngine-eulwqzvrbtommlghsveeumzifrct/Build/Products/Debug -DDEBUG -include /Users/murf/Library/Developer/Xcode/DerivedData/MGTwitterEngine-eulwqzvrbtommlghsveeumzifrct/Build/PrecompiledHeaders/MGTwitterEngine_Prefix-domzcusankbpdrcyelqtaigpwofq/MGTwitterEngine_Prefix.pch -c /Users/murf/Downloads/mattgemmell-MGTwitterEngine-e40658f/TouchJSON/Source/JSON/CJSONScanner.m -o /Users/murf/Library/Developer/Xcode/DerivedData/MGTwitterEngine-eulwqzvrbtommlghsveeumzifrct/Build/Intermediates/MGTwitterEngine.build/Debug/MGTwitterEngine.build/Objects-normal/x86_64/CJSONScanner.o