We've not had any identifiable zombies since 24th September. Revenue is up 40-50% above trend since that date. On the Google side, that's made up of a happy combination of more traffic, better conversions and substantially increased order value. Over half the rev increase is due to the order value increase (25-30%), so the next referral shift will probably wipe that out.
We've had a couple of wobbly days since then, but no zombies at all.
We did have a big (and I mean HUGE) jump in non-Google zombies, but have since identified that tricksy Inktomi Spider as the culprit.
**Edit to add
Yes, I think zombies are indicative of thottling by an unidentified mechanism.
Yes, I think our traffic was being throttled.
Yes, I think the recent flurry is the throttle being set to a higher level (+10% net referrals)
Yes, I still think we are still throttled.
And yes, I realise that this is a somewhat contraversial view