Sharing Outlook mail rules

In Tools|Rules and Alerts..., click the Options button on the RHS. There's an Export button on that dialog that allows you to export your rules.

I agree that this is a deficiency in Outlook. It looks like not much has changed as of outlook.exe version 15.0.4711.1003.

There's a 3rd party plug-in called "Power Rules Manager" by Sperry Software that appears to, among other things, allow import/export to an editable XML format. I haven't used this tool myself since it appears that it would require a separate license for every user that wanted to either create or use share-able rules.