They've been talking about building semantics into internet for the longest time. There's huge potential: imagine going to this blog post and just right click and hit "copy" and then go to your own blog and hit "paste" and then you ended up with this post automatically linked to your new blog post, with all the metadata such as submission dates, comments etc all fall into the right place!
Unfortunately, for efficient flow of structured flow of data (and ultimately achieve data portability) means alot of standardization, and none of that has gained any momentum till now.
See how gd ol' Bill explains it.
Or see it for yourself (Live Prototype).
Microsoft's CTO take on the idea.