As a vendor in the UK, we have been integrating the CUI for the last few years. The quality of the guidance is mixed - there is good evidence that having a "Patient Banner" in a consistent format prevents "right thing, wrong patient" problems. However, a lot of the evidence supporting the other guidance is sketchy. They also lean heavily on MS implementations of the guidance which I would think most vendors will avoid because it does not likely fit into their technology stack (Silverlight / WPF).

However, the real problem is that the market does not value good usability. We are lucky if a potential customer has even heard of the Common User Interface, let alone specifying it as a requirement on a tender.

The "ghetto" effect described by another poster is largely down to the "market for lemons" around healthcare IT, in the UK at least (many different vendors promising a silver bullet to hospitals with no experience in procuring such things - they just pick the cheapest / "least risky").