Greetings,
I realize I am mentioning Exchange 2010 in this post, but I believe this to be an Outlook issue.
I recently tested the Exchange 2010 feature of being to publish one's calendar to the Internet as either an ICS or URL. The URL opens the calendar up just fine in a web interface, and one can then subscribe to the calendar either using the subscribe button on the web interface, or by using the ICS extension directly.
The issue is once the calendar is displayed in Outlook, it never seems to update, even after 24 hours. The only way I have found to update the ICS is by removing the calendar and re-subscribing to it. Is there some way to get Outlook to periodicaly auto-refresh the external ICS calendar? Otherwise it seems like you aren't really "subscribed" to it, but rather took a point in time snapshot of it which will not be clear at all to our outside user base.
Thanks!