GeoServer is one of the most popular web mapping / web services server, and it just got to version 2.5.

The key features according to the announcement:

• WCS 2.0 and WCS 2.0 Earth Observation have been added
• The addition of a batch importer to making setting up GeoServer easier
• High performance PNG encoder based on PNGJ library (Andrea Aime). Improved JPEG performance using libjpegturbo available as an optional extension
• Use of ST_Simplify to improve PostGIS rendering performance
• New implementation of GetFeatureInfo that takes into account symbol shapes, offsets, and dynamic line widths into account