In recent years Apple has maintained its crowd busy with frequent OS updates, first came the original Mac OS X 10.0 launched in March 2001, then while Puma (10.1) was a free update, Jaguar (10.2) and Panther (10.3) both have come to a cost to users, both selling at US$129.
With one more update planned by year's end (10.4 - Tiger) Apple's chief software technology officer announced it will take a longer period of time for the next version of Mac OS X to appear, easing up its update frequency a bit.