With the announcement of MobileMe, we looked again at whether we can replace Exchange on our backend. The mail is interchangeable and the contacts we have aren’t shared, so the only function we really need is a shared viewable calendar that works online, offline when you are on a Macbook, on a Blackberry and on an iPhone.
Here is the current state of the world (the short conclusion is Exchange isn’t replaceable):
* Google Calendar. Only has one-way subscribe to iCal. You have to use a third party like BusySync or an open source product to do two way. On Blackberry there is a manual sync applet you have to hit constantly to update the Blackberry calendar and on the iPhone, there is no sync to the calendar there, you have to access the website. It does however let you look at other people’s calendars, so is nearly there if it could work offline on Mac, Blackberry or iPhone.
* MobileMe. It will bidirectionally sync to iCal and to Outlook for that matter as well as iPhone, but not to Blackberry. However, it doesn’t seem to allow you to subscribe and view other calendars, although this is a little unclear. So it could be a solution if we drop Blackberry support and only use iPhones.