I got this error when I press build+debug:
ld: duplicate symbol .objc_class_name_BlogTableItemCell in /Users/fabian/Development/Workspaces/iphone_experiments/xcode_build_output/MausLog.build/Debug-iphonesimulator/MausLog.build/Objects-normal/i386/BlogTableItemCell-3733583914888A7B.o and /Users/fabian/Development/Workspaces/iphone_experiments/xcode_build_output/MausLog.build/Debug-iphonesimulator/MausLog.build/Objects-normal/i386/BlogTableItemCell-3733583914888A7B.o
collect2: ld returned 1 exit status
Command /Developer/Platforms/iPhoneSimulator.platform/Developer/usr/bin/gcc-4.2 failed with exit code 1
You could also get this error if you mistakenly let Xcode's auto-complete for #import statements specify the '.m" file for the 'duplicate' class instead of the '.h'.