We will be releasing the public beta for Q1 2009 about a week from now. This new version will feature both the RadFileExplorer as a separate control of the RadControls suite, as well as it being integrated into the RadEditor FileBrowser dialogs.
The RadFileExplorer does feature already a multiple file upload, using the RadUpload control.
As you correctly noted, however, DHMTL technology does not allow to select multiple files in the "Choose file..." browser dialog, so choosing several files requires opening the dialog several times.
the Telerik team
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