[jlgreco]

Reddit ads are pinned to the top of the page but allow comments. HN ads float with the rest of the links, but don't allow comments.

Either has their pluses and minuses.

[gus_massa]

In HN they don't float. They go down slowly in a deterministic way. (Perhaps the details of the algoritm have changed a little.) From http://ycombinator.com/newsnews.html#12may11 :

> Now instead of being ranked by points, jobs simply start at position 4 and slide down the page at 4 positions per hour.