IBM updated an article entitled "POWER to the people" which runs down the history of the Power Architecture which developed into the PowerPC processor used in Apple's Macintoshes.
The PowerPC came from the Apple, IBM, Motorola alliance and introduced in 1993, the PowerPC saw its first commercial use in the Power Macintosh 6100.
Since 1993, the PowerPC ecosystem has of course evolved; Apple is no longer actively involved in PowerPC, and Motorola's PowerPC (and other microprocessor) development work has been spun off into the independent semiconductor company known as Freescale.
In summer of 2005, Apple announced it would be abandoning the PowerPC processors in favor of Intel processors. The transition is expected to begin as early as January of 2006.
Freescale and IBM are moving on with their PowerPC processors which may even see a name change sometime in 2006, according to this article:
Top-of-the-line custom processors, such as the next-gen Microsoft® Xbox 360® processor, are based on the PowerPC architecture, and IBM remains firmly committed to the PowerPC family as an important component of its microprocessor lineup (note that Freescale hints the PowerPC might undergo a name change in 2006!).