I'm preparing specs for a home server with 8, then 12 hard drives and port multipliers quickly came into the picture.
I was looking for the same info.
I don't have a definite answer to your questions.
the short answer: yes it does. even the ICH9 did.
The long answer: maybe.
first, you have to check what ICH10 you have. Read this, page 44:
if you see AHCI, then you have FIS
I don't know where the P45 belongs to.
why? because AHCI on the ICH10 is complant with AHCI V1.3, that says it's FIS
(see 1.3 specs here: http://download.intel.com/technology/serialata/pdf/rev1_3.pdf)
But I don't have enough tech knowledge to confirm all of this.
Also it seems that BIOS implementation also impacts this feature.
I wish someone from Intel could make this clear.
Please this post live if you found more information.