Where is that $200 million in Facebook’s 2008 capex going? According to recent research by Data Center Knowledge, at least $10 to $12 million of it is going toward the lease of one new data center alone – an 86,000 square foot facility in Santa Clara custom built by Digital Realty Trust.

Data Center Knowledge has the info on Facebook’s data center providers:

• Facebook has been hosting servers at Terremark’s NAP West data center facility in Santa Clara since 2005, when it signed a multi-year agreement with the Miami-based provider.
• Last fall Facebook leased an additional 10,000 square feet of space in a new facility built by DuPont Fabros in Ashburn, Va. The lease is for the second phase of the $375 million facility, 300,000 square foot ACC4 data center, a state-of-the-art facility backed by 32 diesel generators.
• Facebook’s appetite for high-density, energy-efficient servers has boosted its business with Rackable, which in October identified Facebook as one of its four largest customers along with Microsoft, Yahoo and Amazon. Sales to Facebook helped Rackable post the fastest one-year sales volume growth in a Gartner survey.

As everyone remembers from the case of Friendster a few years ago, good system architecture can make or break a social networking site. While Facebook’s data centers won’t rival Google’s multi-billion dollar annual investments, it sounds like Facebook is building significant expertise in scaling up its data centers. Should make for some interesting systems work.