Olympus has updated the firmware for the E-M1X, E-M1.2 and E-M1.3, and the E-M5.3 today. The updates include the addition of focus stacking with the new 100-400mm zoom. They also updated some kind of IS compatibility between body and lens. It’s not IS sync, but they have optimized operation it seems from the description. Nothing else seems to have been updated.
If you aren’t using that lens or don’t plan to, no technical need to update at the moment. If you are about to go on a trip or a big shoot, I always recommend waiting until you return to update. Just in case this release introduces bugs. Especially since the new lens is not even on sale yet.
Also, if you shoot with the 12-100mm Pro, that lens has a firmware update today as well. It improves autofocus functions during video.