Thanks for being the first commentors (sic?) I’m sure there are aspects of social networking sites that could be offloaded to a public cloud or CDN (or both in the case of Amazon or Rackspace), but they still will need to invest huge amounts in their own infrastructures for the reasons you gave.

That said, they definitely could, should and do incorporate private-cloud software in their own data centers.

Your article seems to have already answered that: “Social network sites can’t look to the cloud to help them solve their infrastructural woes.”, and the 2nd to last paragraph.

And I agree.

Clouds are great for simple or out-of-the-box sites. Even high-traffic, simple, sites…or pieces of sites (eg. serving images from a cloud). But ^^^a complex site has such a variety of applications and processes it’s nearly impossible for one cloud provider to support everything required^^^.

In addition, sites like Twitter, MySpace and FB tweak to the umpteenth degree and end up riding on the OS razors edge.
See FB Haystack: http://www.facebook.com/note.php?note_id=76191543919