We are just back briefly from an U/W photo cruise through Komodo National Park. This trip I tried the new Olympus 60mm macro lens (M.Zuiko 60mm f/2.8 MSC ED Macro Lens). I used it in the standard Olympus port that came with my PT-EP03 housing, it fits perfectly - almost like Olympus planned for it to be the same length as the standard kit zoom lens (the 14-42mm II lens), which also fits in this port.
I have been using the 45mm Leica macro lens (Leica 45mm F2.8 DG Macro Elmarit Aspherical Mega O.I.S) for a few months now, so it was good opportunity to compare them with the same camera (Olympus E-PL2).
What I found was that I liked the Olympus more than the Leica 45mm lens. With the extra focal length (60mm v 45mm - which gives a narrower angle of view), I could stay a little further from subjects that don't like a lens pushed right in their face (and swim away), this was to me the big advantage over the Leica 45mm macro lens. Also the lens is cheaper (significantly), and doesn't need another port (the Leica 45mm does to work effectively).
Although I must admit the Leica lens feels like their is more metal and glass inside, the Olympus is quite light and I'm sure has some plastic in-place of metal inside and out! Image quality wise, well I am fairly critical, but I don't see any difference between them. I have checked Chromatic Abberation, Focus, zoomed at various sizes in Adobe Lightroom and I think it would only be a scientist who could pick the difference!
I've uploaded some photos taken with the 60mm lens (and will continue with more) to my Flickr Photostream, also check-out the Underwater Micro Four Thirds group on Flickr, where other photographers from around the World display their work with these camera's.

Another of our late afternoon dives paid-off yesterday. With a pair of Rhinopias Scorpion Fish found resting together on a sand/rubble slope near Amed. This pair appeared to be very different in colour in the deep water, one in purple, the other in brown. But our strobes revealed their true colours of Pink and Red/Orange.
Our good friend French marine biologist Vincent Chalias was with us, testing his NEW 105mm Sigma macro lens.... while I am still waiting for my 60mm Olympus Macro lens to fly across the ocean from the USA.... as Olympus Australia seem to think we can wait for 6 weeks for their slow boat from China. These pics were taken with my Leica 45mm macro lens and Olympus E-PL2 PEN camera.