As others have mentioned, vokimon's answer is great but unfortunately Google Maps is a bit slow when there are many SymbolPath/SVG-based markers at once.
It looks like using a Data URI is much faster, approximately on par with PNGs.
Also, since it's a full SVG document, it's possible to use a proper filled circle for the dot. The path is modified so it is no longer offset to the top-left, so the anchor needs to be defined.
Here's a modified version that generates these markers:
var coloredMarkerDef = {
svg: [
'<svg viewBox="0 0 22 41" width="22px" height="41px" xmlns="http://www.w3.org/2000/svg">',
'<path d="M 11,41 c -2,-20 -10,-22 -10,-30 a 10,10 0 1 1 20,0 c 0,8 -8,10 -10,30 z" fill="{fillColor}" stroke="#ffffff" stroke-width="1.5"/>',
'<circle cx="11" cy="11" r="3"/>',
'</svg>'
].join(''),
anchor: {x: 11, y: 41},
size: {width: 22, height: 41}
};
var getColoredMarkerSvg = function(color) {
return coloredMarkerDef.svg.replace('{fillColor}', color);
};
var getColoredMarkerUri = function(color) {
return 'data:image/svg+xml,' + encodeURIComponent(getColoredMarkerSvg(color));
};
var getColoredMarkerIcon = function(color) {
return {
url: getColoredMarkerUri(color),
anchor: coloredMarkerDef.anchor,
size: coloredMarkerDef.size,
scaledSize: coloredMarkerDef.size
}
};
Usage:
var marker = new google.maps.Marker({
map: map,
position: new google.maps.LatLng(latitude, longitude),
icon: getColoredMarkerIcon("#FFF")
});
The downside, much like a PNG image, is the whole rectangle is clickable. In theory it's not too difficult to trace the SVG path and generate a MarkerShape polygon.