To add visuals to the concept I found this vid on youtube http://www.youtube.com/watch?v=3DF_Y6YbvnA
The first part - Unsoku Undo is the basic footwork and posture practice. The second part is an exercise in using tegatana (handblade) along with basic footwork.
Very interesting video. 'Unsoku undo' is quite similar to what I was taught, but the range of movements was more extensive... I guess it boils down to the school's emphasis on kata... although the Aikikai schools I've visited do not seem to focus on empty-hand kata...