Though I have not read the whole of it, the competency model and case study of microsoft seems interesting..
Where the basic definition of competency is concerned, interest is given in the end after Intelligence, education, expereinced ethics. According to Harvard based consultants, the desire of any person to stay on in a job depends on deeply embedded life interest, abilities and values in that order. It is a different perspective. Other researchers also insist on the importance of interest- all links on my blog-
http://mypyp.wordpress.com/
You can draw your own conclusions.