Apple is claiming Mac OS X 10.4 Tiger "will be the most important release for developers since Mac OS X was first released in 2001." I'm hardly a Mac developer, so I'm not in a position to say, but the Developer Overview has some exciting dev-oriented details and pretty pictures. And if you're really interested, attend a free Tiger Tech Talk.
This is BrainLog, a blog by Dan Sanderson. Older entries, from October 1999 through September 2010, are preserved for posterity, but are no longer maintained. See the front page and newer entries.
November 3, 2004