I too use a Mac but am using it on Trulia right now. You may have a old version of Safari because I am using the newest version right now. It could be the Mac itself, maybe you can't upgrade to the newest version of Safari if your Mac isn't a newer model with an intel processor chip. If you do have a Mac with an intel chip, you might want to consider loading windows and using parallels to access the window operating system. It works great, but you need 2 gigs of RAM to pull it off. It works with 1 gig, but is pretty slow.
I should make it clear that I don't have to run windows to get to Trulia. I can get it off the Mac OS using Safari.