Olympus published yesterday a new update for OM-D body. Olympus Japanese website tells what´s new:
Table from http://www.olympus.co.jp/en/support/imsg/digicamera/download/software/firm/omd/em5.html
The most important correction: while shooting video, the IS in body works now with any lens you can attach to the body with adapter. Table speaks about OM lenses but that is just Olympus being careful. User must set the focal length in menu for lenses without electric contacts (in adapter), though.
Sound of gyros practically disappeared as promised. The true meaning of "improved sleep recovery" will be seen when experience is gathered.
Firmware update is started by downloading the latest updater from localised Olympus web sites or http://www.olympus.co.jp/en/support/imsg/digicamera/download/software/
What you need is Olympus Digital Camera Updater (Sep. 2012). After installing updater and launching it, the software tells what to do. Depending on firmware in camera there might be a few update rounds until version 1.5 becomes installed.