It seems as though the IGF has already decided what format the workshops should take. According to the Secretariat, workshops that represent the multi-stakeholder approach of the forum (i.e. with representatives from government, private sector, civil society etc) will most probably be chosen over those that represent only one perspective. For example, if Creative Commons wanted to propose a workshop on "Open Content Licences and Collecting Societies", they would probably have to involve representatives from collecting societies in order for the workshop to be accepted.
http://icommons.org/2006/07/31/the-internet-governance-forum-a-story-in-its-beginning-middle-or-end/