I have to say I'm rather skeptical - the author doesn't say anything about installing the special "late 2012" version of OSX 10.8.2[1] which supposedly contains the functionality. Moreover, as far as I can tell, he's just combined the two drives into a JBOD logical volume (with a total size of the combined drives). So the first 120GB of the volume sit on the SSD, the remainder ends up on the HDD. There's nothing dynamic about it. None of the "benchmarks" seem to disprove this at least, although it's hard to tell until we know how a "real" Fusion Drive behaves.
Make sure you also read the other blog posts in his blog. He _proves_ that those chained disks transfer popular files to the SSD when they're accessed more often after a while. He is even on it to show that this technology is file system agnostic and runs even with ZFS, he also found that its block based rather than file based: https://twitter.com/jollyjinx/statuses/263638394721161216
