I've just converted a 2009 and 2010 MacBook Pro to Fusion Drive by replacing the optical drive with a second disk and adding a SSD. The machine is now extremely fast to boot, has significantly more storage capacity, and disk-related processes now finish in a fraction of the time. Great for local-file imports and exports in FMP.
Making the Fusion Drive was quite simple (after converting the optical drive into a second hard disk) however getting BootCamp to create the DOS partition and installing Windows was a REAL challenge.
To make the Fusion Drive:
1) Update to OS X 10.8.2 and make sure the volume is without errors etc.
2) Make a full backup of the disk.
3) Buy a new rotational HD and put your current HD into an external enclosure.
4) Install the new HD and SSD into your machine. Put the SSD where the HD was and put the new HD into the optical drive bay converter.
5) Boot from the external HD.
6) Convert the SSD and HD into a Fusion Drive (FD) and format it as HFS+ Journaled. (See Source A.)
7) Install OS X onto the FD. To save a huge amount of time, get the installer to migrate your "old" account and applications from the external HD during the installation process. This takes a couple of hours.
8) Shut down the machine, remove external drive, boot into your new FD. Use System Preferences to set the new Fusion Drive as your default startup disk.
9) Some software may require re-activation (e.g., Microsoft Office). Do it now and not when you get to a client's office and try to open a csv file in Excel.
At this point your machine is running on the Fusion Drive and should be sweet-as, bro. You may want to stop here and not bother with Windows because by far this is the hardest part since your laptop no longer has an internal optical drive. BootCamp will only allow the partition to be created if it sees a mounted Windows install DVD: a mounted ISO file is not sufficient. Hence the need for the external optical drive. However I could not get the machine to boot into Windows from either the external optical drive, nor a USB stick or an external USB or FireWire HD. Hence the need for WinClone.
To install Windows:
1) Connect the original external HD and use WinClone to save your existing BootCamp partition.
2) Connect your external optical drive (see Note 3) and insert your Windows install media.
3) Run BootCamp, it will see the Windows installer and let you create the partition but the installation of Windows will fail because it cannot boot from the disk.
4) Boot back into Mac OS X and use WinClone to restore your cloned Windows to the newly created and empty BootCamp partition.
5) Boot into Windows. Some software may require re-activation (e.g., Microsoft Windows, Office).
1) Fusion Drive puts the BootCamp partition on the rotational hard disk, not the SSD. No choice.
2) Fusion Drive is only supported on OS X 10.8.2 and later. Not in OS X 10.7 or 10.6.
3) I bought an Apple SuperDrive only to discover that it's not officially supported on MB Pros, only MB Airs and Mac Minis. A single-line edit of a unix-y text files fixed this (see Source B). It may be better to get an external enclosure for the old optical drive instead of the Apple SuperDrive.
4) Note that WinClone is no longer free software. Older versions will not work with OS X 10.8.
Obligatory Legal Disclaimer: Perform this procedure at your own risk. No warranties are implied, etc. It's still a hack at this stage.
A) DIY Fusion Drive instructions (just do Part One)
B) Make Apple SuperDrive work with all Macs