Space News reports that ESA's governing body has given tentative approval to the joint NASA-ESA Mars program. Full approval awaits costing out the joint program to ensure that it fits within funds available.
Under the plan, ESA and NASA will cooperate on a 2016 trace gas orbiter and relay orbiter. ESA will also demonstrate a Mars entry and landing system. [This system is likely to be too small for future rovers, but may be the right size to land possible 2020 Mars network science stations.]
In 2018, ESA and NASA will both launch rovers to Mars. Per a recent tidbit from the Decadal Survey meetings, both landers may be delivered by the same sky crane landing vehicle. In this case, the ESA rover will sample the subsurface and the NASA lander will sample the surface and cache sample for a potential Mars sample return mission.