When an issue comes in, the first thing people should ask themselves is "What has changed". With a change Calendar you can see what has been changed in the past and what is coming up. It allows everyone to be on the same page and gives visibility about what the change was and a link back to the change to see if it needs to be backed out, what has changed etc. In NZ a local company created a custom Change calendar for us as a separate website, it works fine but what would be better is that it is incorporated into the portal/vFire/Mobile and allow direct link back to the change requests.