I think he is referring to running different versions with different CLRs side-by-side. It means Platform-as-a-Service friendly. Since in PaaS you usually don't own the machine, you just run code somewhere. You don't want to be tied in with is framework X installed on the machines or not. You want to be able to pull in what ever framework you like, as you would do with node.js for example
I sort of remember that the core CLR didn't really rev that much, in that it spent the longest time on 2.x, with only the data access technologies built on top changing what seemed like every other week. LINQ was the next nice additive.
I don't recall exactly why now, but I know that the term 'strong naming' can still instill terror in me. I guess that all goes away if you can distribute a statically linked lump per app. The cycle continues..
