In one my Rails applications, I allow the user to search for surrounding businesses from their current location. I always showed them a You Are Here marker. The issue I had with this was that the marker was always the icon as the search results. Differentiating these markers is actually extremely easy with ym4r_gm plugin.
First thing is to find a custom icon that you want to use. You can just Google for custom Google maps icons. I chose to use their default icon, just in a different blue. (You can download it here so you are working with what I am working with for this example). The next thing I did was to use the Google custom markers web site to find the proper config options for the icon.