Seaside also has components. But they aren't as brain-dead as the ones in ASP.NET. It's much cleaner and better-designed (I haven't dug into Seaside completely yet, but so far, very clean)

I think Hacker News is using the component/control-based approach with Arc? Just curious.

I thought it was macro-based HTML generation, which is typical of Lisp web libraries.

macro-based alone doesn't imply one approach or the other, or does it? There could be macros for all the HTML tags (table => <table>), or there could be macros for "widgets".

Right, IIRC UCW is (was?) using both components with either html templates or html generation.