One of the first things I did after getting OS X (It was an iBook G4) was to switch to iTerm, an alternative to the Terminal.app that ships with OS X. One of the main reasons for doing this was support for tabs.
I kept using iTerm, from that iBook G4 to a white Macbook, to a unibody Macbook Pro.
But iTerm has disappointed me too many times over the last few months. It tends to crash every now and then. More recently, I've noticed that when I hold down a key, the key repeats without refreshing the screen. That is, I don't see the result until after I let go of the key. This is unacceptable.
Apparently Terminal.app has come a long way, including adding support for tabs (though I cannot select a specific tab with a keyboard shortcut like I can on iTerm). It also seem much smoother, both in the rendering of fonts and in the response time to my input. So, I am giving it another try.