We focused on the following key areas for ArcGIS Server 9.3:

• Openness – ArcGIS Server includes additional support for OGC Services including enhanced WMS support as well as new WCS and WFS support.
• Image Services – A new image service optimized for image delivery.  It supports resampling/compression as requested by the client, as well as delivering both pictures and data for analysis.  This open service supports SOAP XML, WCS, and WMS. In addition, you can publish raster data that is stored in a geodatabase or file system.  We also offer the ArcGIS Server Image extension for people who need to publish large collections of file-based imagery.
• Scalablity – ArcGIS Server supports on-demand caching of 2D map services.  Via the ArcGIS Server Manager, you can define the cache for a service and enable on-demand caching. You can also use ArcCatalog and geoprocessing tools to build the cache for an area of interest and modify a cache to include additional scale levels.
• Security – With the release of ArcGIS Server 9.3, you can manage security using ArcGIS Server Manager. Role based security can be applied to both applications and services, allowing administrators to assign different levels of access to specific groups of users.
• Usability – 9.3 includes a number of enhancements to the Web mapping applications.  These enhancements include creating a more streamlined user experience, new map navigation, and more tools.  We also support map tips on results and additional printing capabilities.
• Accessibility to Web Developers – ArcGIS Server includes an API for mashup-style development with JavaScript.  It includes Web services SDKs for SOAP and REST services, as well as AJAX-enabled Web ADFs for advanced Web and enterprise applications. The documentation has been greatly expanded, particularly for the Web ADF, JavaScript SDK, REST API, and SOAP Web services. At the User Conference, we will be showing a new ArcGIS API for Adobe Flex, which can be used for building rich web applications.