Abrams basically walked through a typical RIA Services app and most of it is familiar to anyone who has studied the RIA Services documentation and walkthrough. However there were several new things specific to VS2010 and the new bits.

RIA Services is now built on top of WCF. Yep, it's a first-class citizen on the stack right next to Workflow Services and Data Services. Brad Abrams said his goal with RIA was to force n-tier dev and to get people into the 21st century. :) That's why (and I'm translating here, he didn't say this) RIA is a prescriptive framework following the 80/20 rule rather than something totally open ended like the vanilla ASP.NET web project template.

The project template is now out of the box in VS2010/.NET 4.0. Also, there's a design view for XAML now. In fact, all the SL controls are on the toolbox and you don't have to edit the XAML at all. My first impulse is one of repulsion -- however, I realize that this is a great time saver for doing a first cut on layout and wiring up controls. You can always go into the XAML and tweak it later.

with a DataGrid and Pager control RIA does not go grab all nn number of rows from the database and bind it to the grid like in early ASP.NET. It takes advantage of LINQ and gets only the rows for the current page. That data is cached locally so if user clicks back arrow to go back to page 1 it's there.

No more XAML exploring. VS2010 has a Document Outline toolbar that shows a visual representation
of the nodes and their hierarchy.

No more rebuilding the RIA Service in order to push the gs file down to the SL client. Changes are reflected right away.