An excellent position paper on web applications from Mozilla and Opera (via).
So much of the stuff I've been reading lately has been about formlizing and standardizing the web. How boring! Useful, perhaps, maybe even important... but horribly boring. It's nice to see them talking about real issues in application development, which is the most interesting direction for the web (the document distribution side of the web works just fine right now).
As far as advanced web-based UIs go right now, we're still in a dark period, IMHO. It's like the table-based layouts of the 90's -- they work, but it's a precarious position, and burdensome and distracting for the developer.
Anyway, I'll have to keep an eye on Web Forms