As a .NET developer, I've oft complained to my coworkers that years and years ago, a Java program could be compiled and run as a desktop app, or in the browser as an applet, or theoretically in other contexts. Microsoft kept not figuring that out, requiring different and slightly incompatible libraries (say, between WPF and Silverlight). It drove me crazy. Same with WPF and Windows Phone.

I see this kind of motion as very positive and recognition that horizontal re-use is a desired feature (one of the reasons people like node.js).