This is old news, in blog time, but Gruber’s response to Jalkut’s comment on the Leopard delay misses a couple points.
That’s right in the middle of the most productive stretch in Mac OS X history – 10.0.0 was released in March 2001, 10.1.0 was released in September, and 10.2.0 was released less than a year after that in August 2002.
It only looks productive if you’re going by the numbering scheme. The features introduced in the increments from 10.0->10.1->10.2 were nowhere near as large as what was introduced in 10.3 and 10.4.
10.0 was unusable. That’s why 10.1 was given away for free six months after 10.0 was released. 10.2 came soon after because 10.1 still wasn’t very good.
If the release version numbers weren’t determined by marketing, 10.1 should have been 10.0.1 and 10.2 should have been 10.1.
As far as I can tell, 10.4 was the first release of OS X where it felt slower.