1. Your speech has more than one overall point (Saving the environment AND supporting the health care program - both points could be used as supporting points in a speech about political philosophy, but then the one overall point is about the political philosophy).
2. You are presenting points as soundbytes instead of stories. When you tell me what you want without showing me why you want it, you are wasting your breath and my time.
3. You are presenting more than one point every 4-6 minutes. In a 60 minute speech, have ONE overall point (saving the environment) and no more than one supporting point for every 10 minute period. Your audience can only take in so much information at one time.
4. If you aren't allowing your audience to Go Ahead and Laugh at least every 2-3 minutes, you need to find the humor in your speech before your listeners transform into uninterested watchers, cartoon scribblers, or Blackberry escapees. When you add to, you'll always need to edit out.
5. You find yourself running out of time before you reach your conclusion - preferably in your practice sessions as opposed to live, paying audiences.
From Rich Hopkins, advice on recognizing that your speech is too long. Whole post contains the tips for what you can do about it.