Note: iCalendar is an IETF standard (RFC 5545) and not to be confused with Apple iCal.
Note: This article explains how to subscribe to and publish iCalendar feeds, not how to export and import iCalendar files, which would be of limited use.
Doodle to Office 365 (Exchange Online)
With your browser, go to https://doodle.com/account#calendars and copy the link from the “Doodle calendar feed (ics)” section, e.g., http://doodle.com/ics/mydoodle/c441dlaaezup2c1e78tylnjulce5c5xs.ics.
In Office 365, right-click on OTHER CALENDARS, choose open calendar, paste the link copied above, and click open.
Office 365 (Exchange Online) to Doodle
Requirement: Your Office 365 administrator must have allowed calendar publishing (cf. http://office.microsoft.com/en-us/office365-suite-help/turn-on-calendar-publishing-so-people-can-share-information-HA102892275.aspx).
Copy the subscription URL from the e-mail, e.g., webcal://email@example.com/e22131eebd874eaeb1a360fe67ead00115512577072615638594/S-1-8-956255342-3721222250-1081149811-113761334/reachcalendar.ics
With your browser, go to https://doodle.com/account#calendars, click on "ICS feed".
Now paste the link copied above into the “Add a calendar feed by URL” field and click "Add".
Afterwards, remember to update your MeetMe settings at https://doodle.com/account#meetme if you have a MeetMe page.