Like I (opaquely?) said last time this came up (http://news.ycombinator.com/comments?id=12380 ) you could try giving each <item> a <description> child with an escaped link in it a la reddit (http://reddit.com/.rss )

Feedvalidator finds a couple of problems, but I'm not sure that they're related.

http://feedvalidator.org/check.cgi?url=http%3A%2F%2Fnews.ycombinator.com%2Frss

Maybe try generating an Atom feed? Atom seems to be much better defined than any of the myriad competing RSS implementations.

Or maybe toss a hyperlink into the description tag rather than the comments tag ... from what I see in the RSS 2.0 spec, comments is a more of a "should" rather than a "must". The spec itself refers to it as an optional element, and Winer (I think) says in a note that implementers "should" support it. Clearly some of them don't. :-)

Someone mentioned below that it's working on Reddit. I just looked at their feed, and it looks like they are indeed putting the comments link inside "description" rather than "comments".