Hive has been running for many months now. We're just moving more data over to it. We can always switch from Hive back to steemd very quickly and I believe this is actually part of the testing plans. More details coming, but this is a very low risk change due to it being so easily reversible and having nothing to do with the blockchain.

Andy beat me to the punch. I do hope so. We've seen hive making things faster and smoother in some cases for a while now already, but tags and follows especially is a biggie, hurdle wise. One week should be enough to suss out if things aren't forwarding properly, I imagine... It just means that people actually have to point their services at it sometime in the next week and see if it all goes tits up. Won't know if people don't try.