Kotaku reports that stockists in Belgium have been unable to buy new titles for rental purposes since June in preparation for the change. As of December 1st, however, it will become completely illegal to rent any games software.
The move came about as a result of pressure from publisher body the Belgium Entertainment Association.
UPDATE: Edge Online is reporting that the practise of renting games in Belgium will not become technically illegal - the BEA is simply clamping down on rental stores renting out normal retail copies of games. However, as publishers in the territory will not sell copies for rent, the practise has effectively been eradicated.