What is the biggest barrier to your move into the cloud?

I stumbled across a document from Greenpeace citing cloud for additional power draws and the need for more renewable energy (http://www.greenpeace.org/international/en/publications/reports/make-it-green-cloud-computing/.)  This is one of a series I’ve been noticing from the organization bastardizing IT for its effect on the environment and chastising companies for new data centers.  These articles…