Ars Techninca recently opened a new forum called “The Server Room”
The first thread I started there was about sysadmin and datacenter books, and I already have some real jewels that I will be ordering soon, I suspect.
From Cisco Press:
http://www.amazon.com/Center-Facility-Business-Networking-Technology/dp/1587051826 ( http://www.ciscopress.com/bookstore/product.asp?isbn=1587051826 )
and this one was recommended to me too:
http://www.amazon.com/o/ASIN/0201702711/tomontime-20 ( http://everythingsysadmin.com/ )