GeoServer is an open source GIS server that propagates geospatially enabled information. Data is ingested as shapefiles, GeoTIFFs, geospatially enabled databases etc. and then displayed using Open Geospatial Consortium standards, namely WMS and WFS. This allows any software product that has a WMS/WFS ingest to accept these served layers, i.e. Google Earth, OpenLayers, ESRI products.
Many users have run into the issue of updating their GeoServer installation with new data programmatically. There is a partial module for a RESTful configuration, but has not been fully implemented. There is also an excellent code sample here that is the basis for this tutorial. However, with 1.6.0, and the new integrated security subsystem, the code no longer functions properly.