Today the Google Maps team announced some important additions to the Google Maps product and its API. According to Nigel Tao, the current version of Google Maps now supports GeoRSS (Simple, GML and W3C Geo) formats -- to import a GeoRSS file, simply "search" for the URL of one. Give this link a shot.
An even bigger annoucement, that developers who create mashups will probably be very happy about, is support for both GeoRSS and KML directly through the API with very little code. For example, to share some photos as a Google Maps mashup, you can create a ximple KML file and easily consume it with the API:
var gx = new GGeoXml("http://kml.lover.googlepages.com/my-vacation-photos.kml");