The 2012 redesigned 15" MacBook Pro will look like the Air, only slightly thicker at the top end, and be as thin as the Air at the trackpad end. It will drop the glass from the display, and have an all aluminium bezel, in glossy and matte.
- 64GB SSD option for storage number 1 (OS, applications, and most recently used files)
- 500GB and 750GB options for storage number 2 (your non-recently used files, music library, photo library etc)
- 4GB RAM on low end, 8GB on high end
- Usual CPU and GPU upgrades, made possible by being thicker than the Air at the top end, but also with more space from lack of optical drive
- No optical drive anymore
- Dropping 13" model
- Only 15" and 17" models now
I think the most important feature will be the SSD and HDD combo. The SSD will store the OS and applications. But also, it will cache the most recently used files. Any file copied to your Mac will go to the HDD. The OS will then cache that file to the SSD in the background, and it will join a limited list of most recently used. If you open and edit the file, the OS will be using the cached version, and when you save it, it will save to the HDD but also keep the updated version cached to the SSD.
Essentially, the HDD stores all your documents and files, and the OS decides which ones to cache to the SSD for faster loading. If you load a file that isn't cached, it'll just take longer, but of course, will be cached to the SSD so next time you open it, it'll load far quicker.
The amount of files that can be cached to the SSD under 'recently used' will be limited by the amount of space available on the 64GB SSD - more apps you have, less space for caching.
If you had more than 64GB's worth of apps (ignoring the fact that the OS will take up some of that, and formatting), then the rest will appear on the HDD. Again, the OS will decide which ones appear on the SSD and which ones appear on the HDD (most used, and biggest/longest to load will default to SSD).
To the end user, it will appear that they only have one hard drive. The SSD and HDD won't show up as two drives, but just one. That way, it keeps the experience seamless, and prevent the user from having to decide which hard drive to use.
Adapted that from previous rumours earlier this year, and I really hope that is something Apple is working on. An SSD+HDD hybrid would be awesome during a time when SSDs are still too expensive.
Also, if you upgraded the internal HDD to bigger storage, it wouldn't screw anything up, because the OS will just see it as more space for documents, rather than freaking out.
Tim Cook will announce this as something along the lines of, "we wanted the new MacBook Pro to have the loading speeds of the MacBook Air, but we didn't want to compromise on storage capacities. We think we've solved this problem, during a time when we're still waiting on high capacity SSDs. We've created a hybrid SSD+HDD setup, that gives a seamless experience to the user. To them, it appears as just one hard drive. But under the hood, we've got a 64GB SSD for the OS, applications and recently used documents...." etc.