I am considering trying out the Oly system, as some of their lenses look interesting. There are f2 lenses at 21, 24, 40 and 100mm, and it sounds like the 50mm f2 macro competes with Leica.
Lens Group
Plus, watching the Oly lenses on Ebay, they're significantly cheaper than the Pentax ones, due to not fitting a modern body. They also look similar to the Pentax M lenses, which I am particularly fond of, with sweet manual focussing, but relatively modern design.
I'd be keen to hear people's opinion of the OM2 and OM4 series cameras, as these seem like a cheap intro to Olympus. It seems that the old Oly bodies suffer from rapid battery drain and the ones which take 1.5v batteries have noisier mirrors than the OM1 due to differences in metering. Although I am really interested in the Oly lenses, it seems their bodies just aren't up to the reliability of my ME Supers, unless you're prepared to go for a ti version, which costs a bomb. Maybe this is the answer?