For those of you who attended the live WebCast (or are watched the recorded version), here's the code for the example that I was putting together.
About the Sample
The neat part about this application is that is not only uses NetAdvantage controls inside of the UpdatePanel, but it then puts the UpdatePanel into an Infragistics Panel. If that wasn't enough, it also uses the Client-Side object model of both the WebToolbar and the WebTree to provide search functionality which results in triggering an Async post from the UpdatePanel. Truly a fine example of interoperability between NetAdvantage for ASP.NET and Microsof'ts UpdatePanel.
A couple of things I never got around to doing with this sample.. I wanted to use the WebResizingExtender to provide splitter functionality. This should be as simple as copy/paste from the AJAX sample in the Samples Browser. Also, I didn't completely think through the searching use case.. If you notice the search capability will only 'find' nodes that are actually visible in the tree. This is because I'm using LoadOnDemand, so the nodes don't actually exist on the client-side until the parent node is expanded. Of course I could turn off load on demand on the tree (there weren't that many child nodes anyway), but there are a couple of other options.. The two I can think of would be to perform the search server-side, or use the CSOM of the Tree to manually expand each node before searching.
Feel free to post your questions/comments here.