I have a project for which I'd like to have someone install and maintain a Hacker News-type site (in a different vertical). I was wondering what the appropriate/best way would be to find someone familiar with ARC who would be interested in helping.
Posting here as you've just done is a good start. :) You might also ask on Hacker News if anyone is interested. Can you say more about the project and what sort of "vertical" you're considering?
