I use the Fotodiox EOS to M4/3 adapter, under $30 from Amazon.com or buy direct from Fotodiox for $40. No aperture control but for F4 constant aperture lenses, it's fine for me. I shoot manual lenses at F2.8-5.6 range, so F4 works fine in regular lighting.
Otherwise if you want aperture control, the Kipon is the only option for now.
+ 1 for the Fotodiox. Simple, cheap and dependable. True is has no aperture control but those are kinda useless on these sorts of adapters anyway due to possible vignetting. Much better is get a set of screw on ND filters.