I'm going to make reference to myself here - but for those interested, read Part III of "Aikido is Three Peaches" on the Aikido Journal website (http://www.aikidojournal.com/?id=846
) which amplifies a lot of the points in this thread, including Dan's thesis that "nage is uke."
One paragraph of particular relevance follows: "There is a lovely paradox here. NAGE IS "UKE." Aikidoka of the highest skill are those created by the most skillful teachers who mindfully place the student in situations where they must learn freedom through responsiveness, kaeshiwaza and atemi implicit (and sometimes explicit) in their every move. If the student and even more so, the teacher, is not aware that this is the purpose of aikido practice, the opportunity for uke to learn how to do real aikido is lost."