Description from here
E-P1 Firmware Ver1.2 has incorporated the following upgrade.
* Reduced time of the MF ASSIST enlarged display to improve operability.
* REC VIEW enabled when the monitor's backlight is set to off.
Just done the update on mine. I haven't tested the official claims yet, but there are user claims the AF speed has been improved too.
Subjectively the AF with 20mm f/1.7 in good light feels snappier. It still hunts in lower light. Putting the kit 14-42 on, it feels about same as always. As I use the 20mm 99% of the time now, I think I'm happy
Subject to real use that is.