I just saw that WMST is supported by the new Flex 2.5 API. However looking at the Flex 2.5 Viewer documentation, it doesn't look like this is a supported feature yet. Can someone confirm this?
Does anyone know if the next version of the Viewer will support WMTS?
Update: never mind. I found the answer in another thread: "WMTS support was added in the API in version 2.5 and will be supported in the next release of the Flex Viewer (2.6/3.0)."