Several executives close to the last-minute dealings between Apple and I.B.M. said that Mr. Jobs waited until the last moment - 3 p.m. on Friday, June 4 - to inform Big Blue [IBM]. Those executives said that I.B.M. had learned about Apple's negotiations with Intel from news reports and that Apple had not returned phone calls in recent weeks.IBM says pricing was the major reason why Apple made the switch. Apple however claims that performance delivery was the main problem with IBM's PowerPC processors.
Besides Intel's x86 processors Apple also investigated other processors but none could please them. One of these was the Sony Cell processor but it is said that Steve Jobs is disappointed with the Cell design, which he believes will be even less effective than IBM's PowerPC.
Source: MacRumors