You can use RadGrid on its own and following the steps from the example implement the drag-and-drop scenario. If you are using RadGrid you will need to flatten the sharepoint list to a datatable before passing it to the grid's DataSource property in the NeedDataSource event. Alternatively, you can use the SPRadGrid control that comes in the Telerik.Ajax.SharePoint.dll part of the installer for RadControls under SharePoint 2010. SPRadGrid can accept a sharepoint list directly assigned to its DataSource property in the NeedDataSource event and will bind correctly to that. The remaining steps are again as in the online drag-and-drop scenario.
Other than that, you are correct in your observation that the TelerikSPRadGrid web part does not feature such a scenario.
Hope it helps.
the Telerik team
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