This is how we are specifiying the control:
<CuteWebUI:Uploader ID="fileUploader" runat="server" InsertButtonID="btnUpload" CancelButtonID="btnCancelUpload" OnFileUploaded="Uploader_FileUploaded" OnFileValidating="Uploader_FileValidating">
<ValidateOption AllowedFileExtensions="doc, docx, pdf, ppt, pptx, pub, rtf, tif, tiff, vsd, xls, xlsx" MaxSizeKB="8192" />
</CuteWebUI:Uploader>
One thing to note, we don't have an uploadtype specified, but the control itself is in an iframe on a page. I'm going to try specifying the UploadType to flash and see if that works.