He seems to be the guy behind Anelegantchaos, a page that allows you to search those hacked emails from CRU that allegedly reveal the great global warming conspiracy. Here's a bit from the whois on the site:
Created On:15-Nov-2005 17:47:05 UTC
Last Updated On:16-Nov-2009 01:26:16 UTC
Expiration Date:15-Nov-2010 17:47:05 UTC
Sponsoring Registrar:1 & 1 Internet AG (R73-LROR)
Registrant Name:Hugh Miller
Its a real guy; at least the email (firstname.lastname@example.org) matches the email of this web developer with Clyde & Forth Press.
On the other hand, Jeff points out that Hugh Miller is also the name of a Glacier.