I've been using maps.google.com/maps/m to view a couple of my own kml files. But when I type your address into the search field it doesn't find anything. I think it might be the "/kml" , the ones that work for me end as a file name ie: "/nearest.kml". I tried /nearest.kml too and nothing. Not sure how they're hosting that kml , but if you can format the link just right on your desktop so that it defaults to download the kml file, that's what should work on the N900.

Hope what I typed helps and makes sense.