Okay, first off, I just wanted to say it wasn't all that bad. Sure, they turned everyone into a zombie, but it was actually kinda fun if you gave it a chance...
There was a lot of chatter in Trade channel about this, some said it was grief, others had some good fun. Once I realized nothing would get done that day, I just let em have at me. I got to blow myself up and everything was good again. Death was another way to get rid of the zombie curse, but then you had to run back and get your corpse. I found this to also be annoying because I wasn't offering to play as a zombie and had no idea what the consequence would be for my death. Finding the healer was also a bit too confusing. I knew where he/she was one day, but the day I got infected, they weren't there anymore. I think an easier way to dispell the effect besides those options would be better down the road.
Some things about future events though. You might want to be a little more selective in what NPC's you turn into something else. It is a bit annoying that if you wanted to ignore what was going on that you could not. Including the players would be okay if we knew what was going on. I had no idea that when I logged in that day, I would be instantly infected. It took me a few minutes to figure out why my spells were not working. Not knowing I was not myself, well was a bit frustrating and confusing. I think the Breaking News or a Login message about what is going on may be useful in the future.
My best suggestions for "Normal" or "Optional PvP" servers would be this. Don't have the event take away all of the quest givers and battlemasters. Also, don't place the fate of other players in the hands of players. Anytime you give us rope, we will automatically hang ourselves. There are plenty of other NPC's out there that can be messed with that it really shouldn't take away from the experience all that much. But if Bobby and Beverly Bluebie want to continue on their normal boring existence, then I feel they should be allowed to do so.