Filtering Google Maps Markers By Category Using GeoRSS

I've got a map set up displaying markers from a geoRSS file. These markers are grouped by category. What I'd like to do is set up text links for the categories that, when clicked, hide all markers except for those in the associated group. Not sure where to start with thi开发者_JAVA技巧s.

I've not worked with geoRSS before, but see this tutorial for how to go about filtering markers by category. There's a version for V3 here - hope that is close to what you're looking to do!