Do pull down buttons confuse users about the actions they perform?

Pull down buttons (if that's their official name) are starting to pop up here and there. For example, if you look at Eclipse it seems that almost everything is a pull down button. Personally I find them misguiding, since the action they perform is sometimes context sensitive, sometimes it just executes the first action on the pull down list, etc.

When is it okay to use a pull down button? Personally I'm having a hard time justifying their existence.