acs-events should really provide the utility to transform an event into iCalendar format as well as the download filter. Calendar is the only client of acs-events at the moment but there will be other
clients as well. For instance, the SDM will want to create releases with dates noted in acs-events. While you'll be able to see these from the calendar page or portlet, you'll also see these in the SDM and there's no intrinsic reason why we'd want to force users to go to the calendar page/portlet in order to synchronize. The SDM should be able to provide the UI to download (say) upcoming release dates into Outlook, too.
Having the "create iCalendar" utility in acs-events would make this
easy.