I was just browsing through the menus of my Nevada snv_103 and I stumbled upon an entry I'd not seen before - Terminator. So I ran it. At first I was quite disappointed as it just looked like a normal Gnome terminal; then I right clicked and saw the options to split horizontally and vertically. Wooohooo!!! A "multi-terminal in one window" terminal, with tab support too:
This has instantly been promoted to my terminal of choice and replaces a script I wrote that opens 4 terminal windows and then uses wmctrl to resize tile them on my desktop.
All I need to do now is find out how I can get Terminator to open 4 equally sized terminals in one window, in one command, and I'll be even happier.