D'Arcy has a post about teachers vs. speakers, which is a topic that came up a few times during DevTeach. My thoughts about this are fairly complex, but let me see if I can express them in a coherent fashion.
There is a definite difference between teaching and speaking. I like to think about speaking as a show that is targeted at increasing the knowledge of the audience on the subject at hand. Teaching is imparting that knowledge in an actionable form.
To take a concrete example, after my MonoRail talk, I don't expect anyone to be able to build a site using MonoRail. Certainly not with additional resources to go through. After my MonoRail course, however, I would consider this a personal failure if any of the participants wasn't able to build a site using MonoRail.
A success criteria for the MonoRail talk is that the audience groks the gestalt of MonoRail. They understand the tradeoffs in choosing it, what it would bring them and the overall model that is used.
Frankly, in the space of 60 to 75 minutes, I do not believe that you could do more.
Given those constraints, I do not think that you could do more than introduce a subject and open the mind of the people in the audience to why they should learn more about it.
Imparting knowledge takes time, far lower level of granularity when talking about how to do things, and a more gradual build up of the subject material. It takes much longer, since it is also requires a channel with much higher bandwidth for communication.
Unless the topic that I am talking about can be covered in a short span of time, when faced with the timing constraints of a typical speaking engagement, there is no other option than reverting to a lower-bandwidth, hit-the-high-notes, give-an-impression-not-complete-picture approach.
I like teaching, and I enjoy speaking, and I don't think that there should be a value judgement between them.