Ha! indeed, todo apps are the new hello world. Regarding the .JS frameworks, I actually think it's a good thing that many are being created, this grows the community and the need to solve problems in different ways, more ideas, feedback, etc. Check this review of the most popular MVC frameworks, http://goo.gl/2VhZX

I actually wrote a todo list app as an example (https://github.com/elabs/serenade_todomvc), I'm going to go hide now ;)

All these frameworks make me think of this XKCD:

http://xkcd.com/927/

I'd argue that we're in the third generation already.

I don't follow the js world super closely. What would you say were the first two (rich client/single page framework) gens?

I would cite early attempts at JS-generated views that I worked on in the late '90s/early '00s (and I assume other people were doing similar things at the time) and the various RIA frameworks that appeared on the scene circa '04-'05 spawned by Ajax that through no fault of their own tried to rediscover widget-based portal solutions in JS. See Flex, Laszlo and others. Also tried was XUL, all very limited and one-sided.

What we're seeing today is are mostly front-end MVC solutions that have a more populist approach towards platform and usability as those two have matured substantially due to the current global propagation of a certain genre of apps. I hate to admit it, but Facebook has done wonders in terms of providing feedback as to how much a user will tolerate beyond static HTML as well as educating the user to accept as standard certain classes of JS functionality as they iterate through implementations.