What unlocks with karma, and when?
CalmQuiet: My question would be:  why the secrecy?  HN worried that transparency about the processes of ratings & their "rewards" (which (plus + $5.00) will buy you a cappuccino) would lead to abuse of the system?
I think openness system would allow for HN viewers to discuss the value of different site-karma processes -- enabling the site designers (and all of us) to benefit more from the community's collective genius and experience (on this issue the way it does on others).