There is a new firmware available for several Olympus bodies. Check the list here to see whether your body is eligible for this update :
Joint update service for OLYMPUS E-SYSTEM - OLYMPUS Digital Camera
It concerns neither the E-M1 nor the E-M5II which have been updated in December 2015, but the E-M10 (1 and 2) and previous generation bodies like the E-M5, E-P5 plus different E-Pls.
It seems that the main change concerns IBIS and compatibility with new lenses like the announced 300mm F4.
Edit : checking for eventual lenses updates, I saw that several Panasonic lenses have been updated in December 2015. Mainly lenses offering OIS. You can update them even if you only have an Olympus body.