One of the new features in Exchange Server 2010 SP1 and higher is the ability to share calendars using the industry-standard iCalendar protocol.
iCalendar is a format supported by most calendar clients, including iOS devices like the iPhone and other clients such as Apple iCal and Mozilla Thunderbird. It's also supported by hosted providers like Google Calendar and other mail servers such as Zimbra or Lotus Notes. Although a late entry to the field from Microsoft it is nonetheless a welcome addition, and it makes sharing calendars very simple between Exchange Server users who also have iOS Devices.
Naturally there are some caveats to take note of. Most importantly, Exchange Server 2010 is simply providing iCal access to the calendar that is shared; it's not providing a modifiable interface based on the CalDAV protocol. The iCal access is read only.
Secondly, sharing is not based upon the standard Outlook sharing tools. If you use the default calendar sharing...