This statement:
> An ISO8601 timestamp with a timezone.

is at least a little ambiguous. I think the best thing for data *storage* is ISO 8601 timestamps with offset from UTC info - i.e., YYYY-MM-DDTHH:MM:SS{+-}HH:MM, not a named timezone. This is what is specified in ISO 8601; ISO 8601 does not make provision for named timezone information.

Per our recent discussion, named timezones *will* be necessary for asking users about how they want their data consumed and displayed, so that we can account for DST accordingly, but we should use that named timezone info to store data in pure offset from UTC/ISO 8601 form.