Interesting question. I think some advanced apps already use these techniques. For example we already do event driven things at Netflix.
What this does it make it a lot easier for smaller companies to do it without having to invest in all the infrastructure.
So I think yes, it will be revolutionary in the sense that it will get a lot more people using what I think is the future direction of compute and application building.
No idea, for the time being the only supported language is JS. I'm trying to understand if I can run ruby applications by glancing here and there... Didn't had the time to look into it yet, but everyone seems very excited about it.
Not exactly revolutionary per se, it's an idea that's been around at least as long as shells, and as mentioned in the keynote it's a natural level of abstraction above AWS APIs. The neat part is how this simple idea has been translated to applications at scale.
IMO what's really going to be revolutionary is what we end up doing with it, but we're going to have to wait a bit to find that out :)