The GeoServer team has been hard at work fixing bugs for the upcoming 1.5.2 release. However its not all bug fixes. One very exciting new feature is the addition of GeoRSS as an output format.
The addition of GeoRSS makes the process of creating your own map mashup with GeoServer as simple as ever. Simply point Google Maps, Yahoo! Maps, or Microsoft Virtual Earth at a GeoServer GeoRSS overlay and observe as your data is visualized.
Here is a sample screen shot. More screen shots and information are available here.