The only way this is possible, is if your wife had a mailbox under the hosted exchange domain of your organization. Most exchange platforms don't allow cross sharing of free/busy information.

Outlook 2007 does have a publish feature. This feature does allow you to publish your calendar to the internet. You can also copy the calendar to be mailed.

Both these work arounds will not have their items updated when a change is made to the calendar.

However, Microsoft SharePoint 2.0 and 3.0 does allow the sharing of calendar and documents to none organization users.