There is a new book, "Learn to Program Using Python," by Alan Gauld that might be useful as a text. I haven't seen it yet.
It might suit but doesn't contain exercises as such at the end of chapters, just some general topics for consideration... There is also an errata page set up for it at: http://www.crosswinds.net/~agauld/book I'm hopeful of fixing most (all?!) of the typos etc in the 2nd printing....
All other books that I have seen seem to me to target a more sophisticated audience than I can expect in our introductory course.
Mine should do just fine as a first course it does not go very deep but tries to teach basic principles first and foremost. If anyone does use it in an education situation I'd be interested in any feedback via the URL above. Alan G.