That page has a nice web page and examples where queries can be run. 'The skyline operator' is described in http://www.dbis.ethz.ch/research/publications/38.pdf. It reminds me a bit of the staircase join operator, something on my personal wish list for postgres as well (latest patch seems to have got lost on the internet).
They say they're porting the patch to 8.4devel, but I suspect that since 8.4 has been out for ages and 9.0 is almost released, they've probably lost interest and dropped the work.
I looked a bit in the latest patch. There's a lot of FIXME's and TODO's in it. It adds at least one plan node, so it's probably hard to rewrite into contrib form. That'll probably make it harder to get accepted for mainline postgres, also because the skyline queries can be translated into 'normal' sql (referenced pdf, section 3.1), though the authors claim the performance using skyline is better. Since 8.3 CTE's have been introduced and maybe that makes writing these kinds of queries easier. Also the knngist ordering of 'interesting points' might be a solution for problems in the same ballpark.
