What the...
This is so really wrong.

I was thinking... the board could be distributed with DNS round-robin like nij.2chan.net A x.y.z.1 x.y.z.2 x.y.z.3 etc; but for all of them to have the same content posting would still be needed to go to a central "master" server which MAY become a bottleneck later...

I had the idea some time ago to write an "AJAX" imgboard script and I think that'd be the ultimate scalable:
* Board HTML, JS, CSS initially load from DNS r-r webservers,
* The AJAX script knows about all the servers and queries all of them periodically for posts,
* When posting, it just submits to the r-r, i.e. random server
The point here is that all servers only have the posts that landed there not EVERY post.

Now, ordering of posts will not be preserved and numbering posts in order becomes impossible (without reintroducing the bottleneck)...
So posts would be numbered with GUIDs; maintaining a vague total post count of course is still fine.

Is this worth doing? There aren't many boards that really need such a thing... yet?!

PS. DoS of an individual server is still possible, the AJAX script should maybe query the r-r for updated servers' list so servers can be taken out and then DoS causes NO OUTAGE!

What do you all think? Are GUID numbered posts too much for scalability?