DataCenter Certification
Solution 1:
For people - http://www.cisco.com/web/learning/le3/le2/le41/le99/learning_certification_type_home.html
For DCs itself - http://ssae16.com/ (SSAE 16 is the U.S. successor to SAS70. ISAE 3402 is the International equivalent)
Although not a 'DC' accreditation directly, a lot of datacenters generally have PCI compliance accreditation (PCI DSS).
Solution 2:
Look into SAS 70 Compliance if you want to host 'high value' resources in said Data Center.
Basic Overview:
http://www.sas70.us.com/industries/data-center-colocations.php
Solution 3:
There is a certification for a "secure data centre" by TÜV Saarland. They have TIER-style criteria as well, salted with some additions from the German BSI (federal agency for IT security).
TÜV INTERCERT is a subsidiary apparently marketing an internationalized version of this certificate, a couple of published presentation slides have some more details.