I've got a US and EU launch model... I'm looking at the EU one right now.
From what I can tell, the height of the HDD caddy is around 11mm... that's from the base of it, to the little bit of metal that sits over the HDD (on the side with the handle). The actual bay seems to be 13mm or 14mm... hard to get an accurate measurement.
So a 12.5mm drive -could- fit with some buggering around. If I were going to put one in my PS3, what I'd do is take the HDD tray and cut off the side with the handle and the hole where the blue screw goes in. Then, remove the metal "lip" so it doesn't get in the way of the drive and screw it to the new 1TB drive.
Just remember the connectors go to the rear of the console (so your left) and the fold-out handle has to face you. I think with the two screws in and the handle, it should slot in with a bit of a tight fit.
60GB (120GB WD Scorpio Drive) PS3 (CECHA01, NTSC), 3.7OFW
60GB (640GB Samsung Drive) PS3 (CECHC04, PAL), Kmeaw 3.55, Repaired (Dead Laser)
PSP-1003 FAT, CFW5.00 M33-6 & Prometheus v2
X-Box 360 Xenon (JTAG'ed, 500GB HDD)