Tried out the much-hyped Wolfram Alpha and wasn't too impressed with the simple results of a date search. Maybe it's just me, but the difference between today (May 21) and Feb 24 should be 2 months and 27 days (i.e. counting from April 24), not 2 months and 25 days as Wolfram states.
As someone pointed out, the algorithm seems to be counting March and April as the 2 months. the 4 days at the end of Feb and the 21 days of May, but that doesn't seem intuitively the way people count time spans. Otherwise the difference between May 25 and Feb 24 would be "2 months and 29 days", rather than "3 months and a day".