How would I be able to share my Outlook "internet free-busy" status via Dropbox?
My recommendation is to not use a UNC for a local path because the C$ is an administrative share and thus may not be accessible to the end user.
A better way to use the file:// path is to use it like this:
In Outlook 2010 the following works
First go to File->Options->Calendar
Click on "Free-Busy" options
Click on "Other Free/busy"
Set the location to somewhere in your "Public" part of your dropbox. Such as
Search location should be something like the following and point to the folder where you share your items together with others.
To allow others to retrieve your free busy information you will need to share it in your contact. There is a field in the contact details to do this.
This seems to work, but not always, I guess it depends on settings on the client sometimes proxies and firewall does not allow dropbox in some cases.
I've not actually used this, but from the manual i would guess you use the file:// format to save it somewhere in your public folder, and get the other person to use the dropbox link from the public folder to view/add it