Ask PG: Can I change my handle and keep Karma?

In "A Group Is Its Own Worst Enemy" http://shirky.com/writings/group_enemy.html Clay Shirky explains why this is a bad idea:

"If you want a good reputation system, just let me remember who you are. And if you do me a favor, I'll remember it. And I won't store it in the front of my brain, I'll store it here, in the back. I'll just get a good feeling next time I get email from you; I won't even remember why. And if you do me a disservice and I get email from you, my temples will start to throb, and I won't even remember why. If you give users a way of remembering one another, reputation will happen, and that requires nothing more than simple and somewhat persistent handles.

Users have to be able to identify themselves and there has to be a penalty for switching handles. The penalty for switching doesn't have to be total. But if I change my handle on the system, I have to lose some kind of reputation or some kind of context. This keeps the system functioning."