There's been a lot of attention to the way Windows 8 looks; reader aabelro writes with an interesting look at one way it behaves. The article begins thus: "Microsoft has created a new mechanism for sharing information between applications in Windows 8 called Windows Share. Apps can share text, bitmaps, HTML, URI, files, and other type of data, and the usage scenarios are numerous. For example, the app receiving the information can post it to Tweeter or Facebook[, making] it easy to post information to a social network without actually visiting it."
Here's a short (video) explanation at MSDN