I ran Disc Utility (In retrospect, I'm not sure why -nothing seemed wrong)
Ran the Repair Priviledeges button and now Preview doesn't anti-alias anything! not even images.
No other apps seem affected.
here's a screenie:
does anyone have any experience with this behaviour?
[edit]
Replacing the App with a copy from another machine does not help, nor does restarting, nor does re-repairing the privs.