Discontinuation
The PowerPC G5, which powers Apple's now-discontinued Power Mac G5 and iMac G5 computers, proved to be too power-hungry and heat-intensive to use in laptops. This, along with the stalling development of the G5, is said to be one of the main reasons for Apple's transition from PowerPC to Intel processors. On January 10, 2006, Apple released its first Intel-based laptop, the 15" MacBook Pro. A 17" version of the MacBook Pro followed on April 24, 2006. The 12" PowerBook G4 and the G4 iBook were discontinued and replaced by the 13.3" MacBook on May 16, 2006, ending the whole PowerBook line. However, a replacement for the 12" subnotebook form factor was not immediately forthcoming; the MacBook Air, released in 2008, served as an indirect replacement while the 13" MacBook Pro released in 2009 is the direct replacement for the 12" PowerBook G4.
Apple CEO Steve Jobs noted during the introduction of the MacBook Pro that Apple wants the word "Mac" in the name of all its Mac hardware products.
As of August 28, 2009, the PowerBook G4 stopped supporting releases of Mac OS X newer than v10.5 "Leopard", starting with the release of v10.6 "Snow Leopard" and later, which require an Intel processor, and are consequently incompatible with the G4.
Read more about this topic: PowerBook G4