I've imported a city feed for construction on a Google Map API v3. Unfortunately, the default color is a blue that doesn't convey the "caution" needed for construction. Is there an easy way to change the colour of the GeoRSS overlay? Thanks!
No, there isn't an easy way to change the color/styling of a GeoRSS overlay you are pulling in from another service. KML/GeoRSS features are rendered on the map to look like Polylines, Polgyons, and Markers, but they're not full-fledged objects in that sense. If you look at the KmlLayer documentation you'll see that your options are really limited to showing it on a map and making it clickable.
What you need to do is process the GeoRSS / KML somewhere else and add styling information to it that colors the line appropriately. I would probably implement this in a server-side language of your choice, but you could also try to use JavaScript to parse the GeoRSS and create first-class Polyline objects yourself which you'd have full control over.