I want to start off by saying awesome job. I'm really liking this plugin. Having said that, I wanted to revisit a post you made here: http://wordpress.org/support/topic/plugin-basic-google-maps-placemarks-filter-placemarks?replies=3.
I thought the markers were an overlay and could easily be hidden using jQuery. However, upon testing, it seems that the markers are a little more complicated than that. Is there a way to target a marker after it's been created? When you create a new google.maps.Marker there's no class or anything defined to differentiate the markers. Is that functionality that could be easily added? I was thinking it would be pretty easy to link them to their category since that's how they are being shown/notshown already.