Found this presentation last night (yeah I know it’s about a month old). He talks some about YQL and YUI but the thing I found most interesting is the observations.
What do the end user get out of it? That’s an essential question that still seems to get lost when systems are designed. This (IMHO) is particularly true for visual components and javascript enhancements. Such things seems to get added not because they actually adds some value to the product but because they provide fluff.
The really bothersome situation is when design depends soley on the javascript presentation and then (just as the presentation points out) thinks about accessibility. This is a very backwards way of doing it. Add the fluff later if it benefits the end user. There are no shortness of examples for when this is a good thing. Javascript form-validations is very nice and helpful. No round-trip to the server which means a better experience for the end user.
Anyway, watch the presentation and see for yourselves.