I'm having the same problem as alecjcook. when i put the #includes in an otherwise skeleton sketch i get:
C:\Program Files\arduino-0018\libraries\SDcard\arduino sd card example.cpp:161: error: 'DEC' was not declared in this scope
along with 'HEX' not declared, 'Serial' not declared, 'delay' not declared ...
does the cpp file need some tweaking maybe?