New Autofocus. The E-3 sees the first major upgrade of the ageing 3 point AF system used on all Olympus DSLRs since the original E-1 back in 2003. The new fully-biaxial high-speed 11-point AF system with both horizontal and vertical sensor lines to give a total of 44 different data points from which the focus is calculated. Focus sensitivity is also improved (to -2 EV, ISO 100).
In addition to the new autofocus sensor the E-3 sees the introduction of a new range of 'SWD' (Supersonic Wave Drive) lenses. Olympus is being very bullish about the performance of the E-3 with these lenses, claiming the world's fastest focus speed.