<p>I know I can cycle through my tabs using cmd+{ or cmd+}, but is it possible to select a specific tab (i.e. cmd+3 for the third tab in iTerm) in Leopards' Terminal.app? </p>

Yes it is, you use Command-1, Command-2 etc.
Have a look under the
Window
menu, and you'll see the windows listed with their shortcut equivalent. (The 'clover-leaf' is the symbol for the Command key - also known as the Apple key.)
My apologies - missed the fact you were referring to Tabs first time around. I don't believe there is any other keyboard shortcut to switch between Tabs beyond Cmd-{ and }. Perhaps if that's important, don't group them in the first place? Leave them as separate windows?