We have not yet provided a update of the MOSS whitepaper for "Prometheus" controls. It will be available in the coming months.
There are lots of clients which have implemented web parts based on RadControls.
Usually the most difficult thing is to set the RadControlsDir property to valid location because it is a bit tricky in SharePoint environment. Most of the time we suggest copying the /RadControls folder in C:\Program Files\Common Files\Microsoft Shared\web server extensions\60\TEMPLATE\LAYOUTS and then referring to it as "~/_layouts/RadControls".
Another option is to copy that folder in the root folder of your site and then exclude it from the SharePoint managed paths using stsadm.exe.
Creating a webpart based should be quite simple - here is a short sample:
public class MyWebPart : WebPart
protected override void CreateChildControls()
RadGrid grid = new RadGrid();
grid.ID = "myGrid";
grid.RadControlsDir = "~/_layouts/RadControls";
/* populate your grid based on your requirements */
protected override void RenderWebPart(HtmlTextWriter output)
All the best,
the Telerik team