In the stock Mac OS X python installation, idle is found in /usr/bin, which is not (easily) accessible from Finder and not indexed by Spotlight. The quickest option is to open the Terminal utility and type 'idle' at the prompt. For a more Mac-like way of opening it, you'll have to create a small app or shortcut to launch /usr/bin/idle for you (an exercise left to the reader).
与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…