You know what I hate? My history isn't aggregated in real time across all my Mac OS X terminal windows. You know what else I hate? Typing in long commands in the Mac OS X terminal and then them wrapping weirdly. Especially when I hit the up arrow to go back in my terminal history.
I used to feel this way. Then one day I figured out how to enable this in Bash. Resulted in a confusing mess. Turns out you most likely want terminal sessions to be distinct until you end them.