And the answer is:

"Unfortunately it is not a process of making it available in Exchange
2003. It
is more of a process of making it available to your Outlook 2003 client.

You can accomplish this by having each of the users who want access to
the
calendar navigate to the calendar and select Connect to Outlook from the

Actions menu.

But, before you run off and do this, understand that with Outlook 2003
it is
a 1-way sync process. For example, you can add new items via SharePoint
and
they will automatically sync up with the calendar in Outlook, however
you
cannot go the other way.

If you want 2-way sync you need to have Outlook 2007.