For a company events calendar, you can simply create a new Calendar folder in Public Folders and grant permissions through the Properties dialog for the folder.
Outlook 2007 adds the ability to send calendar files and publish your calendar for sharing. This supports just one way sync - the sender can update the calendar but others can't. If all users need the capability to update the calendar, you'll need to use one of the tools below.
Tools in the Spotlight
Gives managers, secretaries and co-workers an instant, web-based view of where people are, what they are doing, and when they are next available. AgendaX will seamlessly manage multiple time zones and allow global views of staff availability and resource allocation. AgendaX incorporates many features that allow you to take advantage of Outlook calendaring, Active Directory attributes and web views to give you the ultimate corporate resource portal. No client installation necessary and nothing is installed on Exchange Server. Supports all Exchange Server versions. New Version 6 available now!
Save time and money using TimeFleX as your perfect group calendar. Scheduling teams and resources does not need to be complex and time consuming. TimeFleX makes it simple and straightforward. The advanced graphical interface improves visibility into team and resources extending the value of an Exchange or Office 365 implementation. Improve meeting planning efficiency to a maximum for all departments and all requirements along with filtering features by using our extensions Mobile / Meeting Finder / Room&Catering
For additional information on group calendaring, see Maintaining a Group Calendar in Outlook