Release dates

• Mac OS X 10.0: Cheetah, released 24 March 2001
• Mac OS X 10.1: Puma, released 24 September 2001 (184 days after Cheetah)
• Mac OS X 10.2: Jaguar, released 23 August 2002 (333 days after Puma)
• Mac OS X 10.3: Panther, released 24 October 2003 (427 days after Jaguar)
• Mac OS X 10.4: Tiger, released 29 April 2005 (553 days after Panther)
• Mac OS X 10.5: Leopard, released 26 October 2007 (910 days after Tiger)

Ruby trivia

The date calculations above were done in irb:

require 'date'
cheetah = Date.new(2001, 3, 24)
puma = Date.new(2001, 9, 24)
puma - cheetah