Deja vue all over again, in a way, as the M.ZUIKO DIGITAL ED 40-150mm f2.8 PRO lens was first announced when the E-M1 was released but this time it's for real. The press release is here and the US product page is here. There's also a YouTube video introducing the lens here.
Here's the MTF chart:
I'm no expert but comparing it to the MTF chart of the sharpest telephoto zoom I've previously owned, the Canon EF 70-200mm f/4L IS USM, I think this is even better and, don't forget, that Zuiko MTF chart is wide open at f/2.8. So maybe it's been worth the wait, although I could have made very good use of the lens this summer

Bob.