The new MacBooks are the first Apple portable to include a quad-core processor, Intel's Core i7. The devices also include more RAM, iFixit discovered. Thunderbolt, meanwhile, combines PCI Express and DisplayPort into a single connector.
On the new machines, you can chain up to six Thunderbolt devices. For comparison, FireWire supports 63 devices and USB supports up to 127 devices. But as iFixit noted, this might not be an issue since "we're not even aware of six products that support Thunderbolt yet." But if the connection becomes more popular, it might become a problem.
The RAM in the MacBooks is PC3-10600. That's the same RAM found in the 21.5-inch and 27-inch iMacs released last year, but different from earlier Apple laptops, iFixit said. PC3-10600 can be used in older MacBook Pro machines, but the RAM found in those older machines - PC3-8500 - will not work in the new MacBook Pros.