The new Smart car will be the ForFour and there will also be an upgraded Fortwo as well. Both were seen testing in Sweden in the cold weather recently.
The ForFour is a new model and will be similar to the ForTwo rather than being anything like the old version of the ForFour. Instead of working together with Mitsubishi, it will be co-developed with Renault. The result could be a new Renault Twingo. There have been some rumours saying that Renault are not interested in that partnership any more, but the test vehicles not only had French number plates but were caravanning with a Dacia Duster with French registration so it seems that it is likely they are still working together on the project. Nothing official has been said on the matter.
It is expected that the new ForTwo will be available before the ForFour, probably 2014 for the former and 2015 for the latter.