It's not going to be faster than caching[1] and suffers from a lot of potential data loss scenarios.
Yes, you get your 32 or 64 gig of SSD back, but who cares?
Tiered storage is used in enterprise environments to maximize the use of expensive fast storage, or insanely cheap very slow storage. Like say, really really high end PCI express based cards, or really cheap but high latency tape drives. However, this makes a lot less sense in a consumer environment where consumer SSD prices are dropping 50% year over year.
http://camelcamelcamel.com/OCZ-Technology-Vertex-2-5-Inch-VT...
They also make a lot less sense with only two tiers anyway.
So, to review,
1. Unlike the original claim, "fusion drives" are not new technology, or pioneering (since, as you point out, it's been available in enterprise storage systems for quite a while)
2. It's not clear it's actually better than the caching system others use.
3. It's not clear it makes financial sense.
[1] On the read side, you could use the same algorithm for deciding to move to cache as oyu do in tiered storage, and get identical performance. On the write side, you can use the SSD as a data journal and perform writes as fast as you can write to SSD. In a tiered storage model, all storage usually starts out on the "normal" tier, so writes will be slower, reads may be faster.
If they use some weirder model (like data journaling to ssd), then it becomes equivalent to cache (in both time and space usage, not just time) , not "better".