A new release (10606) is out, that you might download on CodePlex.
I quickly tried out the script combining stuff and it works really great. I saved 7 round trip to the server and almost 2 seconds in the page load. You might read more about it on Shawn Burke
I spend a part of this evening fighting with ScriptManager.RegisterClientScriptInclude and had no chance to use it in a way that my javascripts would appear after MicrosoftAjax.js and in an order that I defined.
I finally found a solution, using ScriptManagerProxy and declaratively listing the javascripts in the order I wanted.
If you are using ASP.NET Validators in UpdatePanel consider the post of Matt Gibbs: "ASP.NET AJAX Validators".
ASP.NET AJAX provides new APIs for registering script with the ScriptManager. Using these APIs allows controls to work well with partial rendering. Without them, controls placed inside an UpdatePanel won't work as expected. In previous CTP releases of ASP.NET AJAX, we had a set of validator controls that derived from the v2.0 controls and used the new APIs. This made them work well with ASP.NET AJAX. WindowsUpdate will soon include a version of System.Web that can take advantage of the new APIs. So the new controls which would have been redundant have been removed. However, the update isn't available yet and ASP.NET AJAX has been released. So, in the short-term, the source code for a set of custom validator controls that work with partial rendering is available here.