If there were a Level 0 in E2's Voting/Experience System, it would be somewhat like the situation new Advogato users are in. On Advogato, a new user starts out as an Observer, unable to write stories or comment on stories. (I could be wrong about the comment part; the system may simply hide Observer comments from Guest User. /msg me if you know the correct answer.) A new user must demonstrate her worth by writing diary entries and adding information about projects she has worked on before other users can certify her to level 1: Apprentice.
If E2 followed this system, a Level 0 noder would have to get certified to Level 1 by another noder before he can even create a writeup outside the daylogs. This would tie in with the mentor system somehow; a mentor could review samples of writing in a user's E2 Scratch Pad to see if the new user had promise.