Terminal hangs on startup
You can try deleting Terminal's saved application state. It's in ~/Library/Saved Application State/com.apple.Terminal.savedState. You can also try deleting Terminal's preferences. Those are in ~/Library/Preferences/com.apple.Terminal.plist.

If you don't want to potentially lose the saved state or preferences, you can move them to the desktop before starting Terminal.

In Lion, you can get to ~/Library by holding the Option key while selecting the Go menu in Finder.