I was looking at various 4/3 lens specs today, and it occurred to me that Olympus have never made anything faster than f2
Then, thinking back, I remembered someone on DPreview called . . . erm . . Joe Wiznezki - something like that, talking about telecentricity, and that it wasn't possible to make a properly telecentric lens with the size of the 4/3 mount at anything faster than f2.
I don't know if this is true or not, (not being an optical whizzer), but I'm quite sure that Sigma has pretty much ignored the telecentricity rules and simply bunged a 4/3 mount on their existing lenses.
There has been a bit of talk of Olympus relaxing their rules due to better sensor design, so maybe we'll finally see some faster primes.