If you haven't noticed it by yet, there's a new widget (as seen at the left) on the Terminal app's scrollbar. This is a window-splitting control. To create a split window, click the widget and then drag the resulting divider line to provide a good split between the two portions of the screen.
The area above the divider line is your scroll buffer; the area below the line is the active area. This makes it very easy to look back for previous commands, output streams, man pages, etc. The other effect of the divided window is that the scroll bars are now locked in the buffer portion of the window ... so things like page-up and page-down (and the scroll wheel, if you have one on your mouse) work in the history buffer, not the "active" lower portion of the window. If you're halfway through typing a command and want to look back at something, just hit "page up" until you see what you wanted to see and then keep typing. This is a very useful addition to the Terminal!

