PaulS:
Where did you get this library, which does not appear to have been updated for 1.0?
Looks like it might be one of mine, however the current one compiles OK under 1.0.2.
@OP: try downloading this file:
http://www.gammon.com.au/Arduino/Elapsed.zip
The original one probably didn't have the test for WProgram.h / Arduino.h.