As the others have already mentioned, the home prices within Cupertino are more greatly affected by the quality of the schools than the presence of Apple Computers on site. Also a home price increase that you are suggesting would be predicated on a significant increase in housing demand in the area. That housing demand is unlikely to occur, in my opinion..and here's why:
1. The majority of the Apple employees do NOT live in Cupertino now. Most commute to the campus through private cars or company provided shuttles. You cannot live or work in this area without being forever behind one of the Apple's fleet of "gray lines" (their unmarked, dark gray colored buses and shuttle buses that are a fixture along Stevens Creek, Wolfe Road and Sunnyvale-Saratoga). Why buy in Cupertino, when Apple provides convenient shuttles?
2. Cupertino housing prices are already sky high. Given the demographic of the average Apple employee, buying an older home worth $1.4 million is just not that attractive to the majority of Apple's working population. They will purchase condominiums--there are a LOT of condominiums near Apple campuses that are owned and purchased by Apple employees, but there is not that same demand with homes in the area.
Certainly, there will be a few Apple employees that are interested in buying and living in Cupertino, but because the home prices here are so high now, I don't see a significant population of the workers being able to afford housing in the area for quite some time. What I do see now and what will likely happen in the very near future is that the exit on Wolfe Road in both directions on 280 is likely to become as congested and dangerous as the exit on De Anza Boulevard. Also, traffic along Homestead between Saratoga Sunnyvale and Lawrence Expressway, and in and around Birdland and back along Pruneridge near Tantau is likely to be much more congested and inaccesible. Homes located along Homestead and Pruneridge may actually lose value due to the increased traffic. Having managed properties near Apple, I know that the number one complaint for almost everyone living near Apple concerns traffic and cars. Their employees comprise such a significant influx of traffic daily, that it is the greatest and most oft-noted impact on any neighborhood.
So, for property values, I don't think you'll see much of a housing price increase due Apple's new campus in Cupertino since most of the Apple employees commute into their campus through the "gray lines". You may see some loss of home values for the properties located on or around the main arteries leading into the area (Homestead/Pruneridge/Tantau/Wolfe) due to congestion. Long term, all housing in these areas will continue to rise in value, but I wouldn't expect an abnormal "pop" in pricing from the "spaceship" campus.