Short answer: yes
-- export the root element of the active document
tell application "Adobe InDesign CS4"
export XML element 1 of active document format XML to POSIX file "/tmp/tmp.xml"
-- open in the default XML editor
tell application "Finder"
open POSIX file "/tmp/tmp.xml"
Both technologies "ScriptUI" and "CSXS" / Flex also have palette windows and tree view widgets.