So the model that Art Haddad presented was as follows:
The ArcGIS Server 9.3 ADF is a hybrid platform.
ArcGIS Server 9.3 now uses the Microsoft ASP.NET AJAX library. This is a great library from Microsoft which we have been using in house and it's great to see ESRI now using this. It makes coding a lot easier. ESRI will still be supporting the previous .NET call back framework which we have in ArcGIS Server 9.2, so this is good for developers out there who are familiar with this.
There are a bundle of visual and non-visual controls. All the controls are AJAX enabled. This is ASP.NETAJAX. ESRI is still supporting an extensible architecture with the ADF data sources which is good to see.
You are now able to work with the results controls. The tasks at 9.3 provide better usability. There is a new print task. This is something so many people have been asking for. ESRI will be releasing the source code of these controls as well, so you as a developer can see how they have developed them and you can use this to develop your own custom tasks.
There is improved documentation. The documentation has been enhanced with many more discussion topics and migration strategies.
So what are some of the highlights at 9.3?
To talk about a few of these points. A big improved is the faster map blending. This is when you are blending dynamic and map cached tiles. ArcGIS Server 9.2 maintained a map centric view where as in ArcGIS Server 9.3, each resource maintains it's own.
The web controls have been enhanced and improved. The ADF web controls are scriptable controls which extend the ASP.NET AJAX client-side functionalities. The is a new layer formats section to the MapResourceManager. This allows you to configure a number of aspects of the layers.
There is a new out of the box template which can be created using the ArcGIS Server Manager. This has been updated to use the new controls and provides a cleaner look and feel.
For those wanting to know about migration to ArcGIS Server 9.3, ESRI has put together a nice migration strategy which is available on the ArcGIS Server Resource Centre and as part of the documentation. ESRI will also be providing an automated tool to migrate from web applications created using the ArcGIS Server Manager in 9.2.
The ADF is an object orientated event driven model. There is now the discussions around the call back vs ASP.NET AJAX frameworks.
ArcGIS Server 9.3 is going to be a quality release with a comprehensive ADF. Improved performance and a better/enhanced development experience is coming. Along with this a better user experience is expected.