Terminal.app equivalent of `xterm -e 'cmd'`
With AppleScript, you can do:


on run argv
    set command to item 1 of argv --you can customize this to be constant
    tell application "Terminal"
        activate
        do script (command & "; exit")
    end tell
end run


This will open Terminal and tell it to run a command (Your default settings need to close the window when the shell exits). 
To run this, just use osascript filename.scpt "$command_to_run"