As a language construct within PHP it would be very easy to do the same, but easier to learn and to use. Beside some keyword issues (the RFC uses "use" as keyword, but this will of course conflict with namespaces) I'm wondering what this will have an impact on reflection - the RFC stays unclear about this.

A trait is a free-floating chink of functionality that, instead of being confined to a class (or file) that has to be called on to use it, exists where the developer can use it from anywhere at any time. This helps solve some of the issues with single inheritance in PHP.