I split this cancellation announcement off from the original one, so its not lost in the (valid) questions about mailman data scrubs thread.
Due to concerns regarding list delivery for Wikimania (and the large number of folks traveling), legal has signed off on us delaying the downtime window until AFTER Wikimania.
A followup window will be scheduled at a later date. Once it is determined, I'll ensure the announcement is sent to this list.