Apple's strong customer loyalty and unique position in the computer industry make them an attractive advertising or co-branding partner, but it's hard to imagine Steve Jobs hitching his wagon up to the Intel marketing train. Historically, Jobs has been extremely protective of the Apple brand and careful to avoid anything he felt might dilute it. One of his first actions upon returning to the company was to kill off the last of Apple's clone initiatives for precisely this reason. Intel marketing dollars have undoubtedly helped Dell and HP sell computers, but the ubiquitous Intel Inside logo and accompanying jingle has also contributed to vendor brand dilution across the industry. People may still display a preference for one computer manufacturer over another, but you don't hear anyone talking about HP's new and innovative case design, or the elegance of Dell's CPU cooling system. The only "feature" of a mainstream system people tend to talk about is price, sometimes followed by the processor brand. There's nothing inherently wrong with this approach, but it's definitely not the way Apple does business.
It's possible, however, that Apple is about to shift its branding and advertising focus. Apple may not need marketing funds to appeal to loyal Apple consumers, but there's a lot of software that needs to be ported to, and optimized for, the x86 architecture. Lower system prices could also help Apple retain more users who might otherwise purchase from another vendor, and of course, Apple would like to see its share of the PC market improve. No matter what happens, it'll be fascinating to see how the partnership develops—can two companies with a long history of aggressive branding play nice together?