If you don't read any other documentation, you might want to at least read these "Three Potential Initial Gotchas":
1. Requires Adobe Flex 4 SDK. 2. You should use Flash Builder 4 beta 2 as your IDE. 3. If connecting to a 9.3 server, you need to set the useAMF property to false for Query, Geoprocessor and FeatureLayer.
In the API Library download (the "zip") is a rough/draft cluster sample called ClusterFunction.mxml. We haven't included it in the list/TOC of samples online because our clustering implementation is still a bit rough and the sample isn't that great. There might be a few API changes to the first beta when it comes to clustering ...
Just noticed a bug on that, and possibly all the sample pages. Try moving the mouse from the TOC panel over onto the map. Bam, scroll bars appear! Even worse if you move the mouse into the map pane from the bottom. If you do it slow enough, the scrollbar flickers on and off a million times until you've passed through! Perhaps related to the problem I'm having? (see most recent thread)
Yes, that is a problem with how we are presenting the individual samples inside our Samples Explorer in regards to those scrollbars. For now, you can also go straight to the sample in action by going directly to the SWF.