I heard there's a "Speak" option. But it's not in my menu. Why not?

If your device either doesn't support Android's Text-To-Speech (TTS) or doesn't have the Google Play Store installed, this option won't appear.

This is because in my testing on Froyo w/o the market installed, I got a crash when TTS tried to download additional components. So having it is a requirement. Since the Google Play Store is installed on so many installations of Android (and it's probably where you downloaded DubScript to begin with) most users are probably not affected by this.