The rumor site is saying that Olympus may (FT2) be making a 150-400 PRO telephoto zoom. No specs are known at this time, but it makes sense. given the gap in Olympus' focal lengths in the telephoto range. The PL 100-400 appears to be a hit, and it makes sense that Olympus wants a piece of that pie (the 40-150 + TC still only has half the reach of the PL zoom, and the 300/4 PRO, while an excellent piece of glass, and be a bit constraining due to it being a prime). I'm a bit surprised that it starts at 150mm and not 100mm (to pair with the 12-100 PRO). There's no way that it'll be an f/2.8 to pick up where the 40-150 leaves off. Up to this point, Olympus has not made a variable-aperture PRO lens. Will this one be variable aperture? An f/2.8-4 would still make it a monster. Maybe f/4-5.6? Do they make it a constant f/4 (and if so, how does that affect sales of the 300/4 PRO)? Keep in mind that this is only an FT2 from a new source, so there's no telling whether this is true or not, but given the success of the PL 100-400, I would not be surprised if it were indeed a lens being developed. I think the big question is what will the speed of the lens be? I can't see it being a constant f4 (just look at how big CaNikon's 180/200-400 f/4 lenses are). My guess is that it'll be an f/4-5.6 with PRO-like optical quality. That aperture range will help keep the size of the lens down, and also help protect some 300/4 PRO lens sales (for those that need the extra ~2/3-1 stop at that focal length.