[geeks] Impressive...

[nate at portents.com]

> What about SATA 2.5 HDD, aren't they smaller

Yes.

> and much more expensive than 3.5 ones?

More expensive per GB, but not necessarily more expensive when you
consider the data density you can achieve.

Think about your hot-swap enclosure options - you can fit four 500GB 2.5"
drives in one 5.25" bay, so 2TB per 5.25" bay.  You can fit five 3.5"
drives in three 5.25" bays, or 4.5TB.  In that same space you can fit
twelve 500GB 2.5" drives, for 6TB, so higher data density (and more RAID
options as well).  In about 20 days the 7200rpm 500GB 2.5" SATA drives
will be hitting the market at about $150 a drive.  The cheapest per GB? 
No, but you can do more with them in less space.

> Is that changing already or will on the near future?

It's not changing too much, because it takes some very dense platters to
get high capacity in a 2.5" format.

> What about power usage?

Lower, because there's typically less mass involved and most consumer 2.5"
drives are aimed at the portable computer market.

- Nate