I saw several people from 18F present at Code for America Summit the other week, and my understanding is that the regulatory overhead involved in launching new government tech services (something like 4000 pages of relevant regulations to comply with) is so large that it's usually a boondoggle. Part of what they are doing is building services with that regulatory compliance built into it, so agencies don't have to slog through all of that for every little thing they want built.

Governance, Risk and Compliance. Even if the private sector does GRC better than the government, they (the gov't) at the very least have control. Not to mention their stack appears to be mostly open source (Docker, CF, etc). This makes total sense and is a "best of both worlds" approach.

The cloud.gov platform is built on top of existing tooling and platforms (Docker, Cloud Foundry, AWS). It's possible recommendations and documentation for quickly deploying sites and services using these platforms is lacking, or changes too often to be provided as a supported, recommended solution to a large set of small teams.