This is great, but I'm ever so slightly disappointed that they called it the Lambda Runtime API instead of Common Gateway Interface. [1] It's not quite the same, but it definitely gives me an everything-old-is-new-again feeling.
Seeing this takes away one of my biggest comparative advantages, but I'm happy to see that at least I was not wrong in thinking this feature would be important for developers.
CGI still has the advantage of being an open standard, locally testable, and not vendor specific.
https://en.wikipedia.org/wiki/Common_Gateway_Interface