2008/10/31 James Mckenzie jjmckenzie51@earthlink.net:
This would not work on Macs as /etc/hosts is locked to admins only and would be a problem to implement.
I don't see how that's a problem, or how that's different from eg. Linux.
More on-topic, I don't think it would be hard to do some LD_PRELOAD hacks on getaddrinfo(), gethostbyname(), and whatever else is appropriate.