Rain cover suitable for MFT cameras.
Try this one....it has a try before you buy offer....they will ship to you before you have to pay...the material is like a thin shower curtain, less stiff, and depending on which one you get, you could use a flash with it. Better than nothing when really raining.
I bought that when I got my E-510 a few years ago (an E-1 certainly spoils you in terms of worrying about weather), but I rarely used it. Instead, I just put the E-510 in a ziplock (tm) bag when the weather gets damp, just like I do with the E-P2. The problem with rain covers like that is the lens sticks through. That is ok if you have a weather sealed lens like the Olympus 14-54mm lens, but I would imagine that on a non-sealed lens, sooner or later water will get in the lens.
On ebay, I see waterproof bags by Bingo that you put the camera in and then seal up for about $20 (and more expensive bags made for DSLRs). The question might be how clear is the bag that you shoot through, but if you only put the Pen/Panny in the bag when it rains, and use the little silicon bags to wick out moisture, it may be acceptable.