Mac OS X 10.3, aka Panther, will not be a 64-bit operating system, despite running on a 64-bit processor, the PowerPC 970 aka the G5.

Instead, the next major release of the Mac operating system will be a hybrid, much like version 10.2.7, codenamed 'Smeagol', which Apple has running on its pre-production Power Mac G5 machines and with which it will almost certainly ship production units.

Read more: The Register (http://www.theregister.co.uk/content/39/31600.html).