Well, I've been waiting for these > 500GB drives for months. So here it is, maybe not quite.
I measured the HD bay in my Macbook 13" (removable battery model), and there seems to be indeed enough space for a 12.5mm drive. So I ordered one 1 TB external USB today, and I'll get it tomorrow.
Now, something freaked me out today as I was looking at guides to take out the drives from the My Passport 2.5 USB units by WD. It seems like the drive in there might have been modified so that it won't retrofit as an internal HD.
That would suck big time. For some reason one cannot purchase the internal 1TB or 750GB right now, and I need the drive ASAP before I travel next week so I don't have to carry around an external USB. So I purchased the external version even though I really need just an internal HD ASAP.
Anyhow, I guess I'll find out tomorrow when I rip apart the drive to see what it's in. Let's hope it's a regular drive, and let's hope it does fit!!
I'll report of my findings here.
Crossing fingers...