I've owned both now and can share a few thoughts and personal opinions. I bought the Olympus shortly after its release and was very pleased on first impressions. It filled the spot between a P&S and SLR nicely. Even my wife was taking better pictures now and we were carrying it around everywhere. I bought the GF1 with the 20mm f1.7 last month and it was then that the EP1's shortcomings became more evident. The following is IMHO and may differ from others.
-EP1 looks way cooler than the GF1
-Panasonic 20mm > Olympus 17mm
-EP1 high ISO (800 and above)>GF1
-GF1 built in flash in a pinch> Olympus has none
-GF1 autofocus >>> Olympus (this is very evident in low light situations and moving subjects)
-EP1 controls and layout>GF1
Overall IMO GF1>EP1 however that may all change if and when the rumored EP2 is released and it addresses some of these issues.
Here a 2 samples from the GF1 and 20mm f1.7 (SOOC w/standard settings)
