I recently submitted their latest: http://news.ycombinator.com/item?id=1129738 and it got upvoted a lot in the first hour (more than others that did make the front page) but for some reason never made it to the front.
Which is a bit sad because I think it was their most interesting one yet. (And the visual aids were extremely well done.)
I wonder if it's you who is marked as a spammer somehow, as opposed to the OKCupid blog.
I can't imagine why someone would want to blacklist that site, but I could imagine HN's capricious, opaque, oft-changing spam filter could have nailed you personally for no reason at all.
About: A collection of interesting charts, tables, maps, and interactive data toys -- with a focus on economics and graphic design. Enormous thanks to the bloggers who help find all this stuff, and the wonderful researchers, analysts, and graphic artists who create them.