Try to execute this:
osascript -e 'tell app "Terminal"' -e 'activate' -e 'do script ""' -e 'end tell' sleep 80000255
in a terminal and tell me what is the result.
Probably they've changed something in 10.8. I don't know and I don't have OSX to try it.
p.s. gdb 6.3 is extremely old and probably won't work correctly. You need at least 6.8 and preferably 7.4/5.