One of the most common things we get asked at HFI, from commercial and government clients alike, is how to measure the ROI for UX activities. We begin many a conversation with new or potential clients by walking them through a discussion of the various different benefits that a UX approach could provide their organization - increased conversion rates, reduction in training costs, improved brand value, etc.
(you can find a nice white paper
and some ROI calculators
on the HFI web site)
Now, having said that we talk to both commercial and government clients about the business case for UX, the particulars do vary. What's important for a commercial client is likely different than that of a government agency. They're likely focused on things like revenue or other transactions. Government agencies are likely more interested in how successful they are at providing more and better information to the public, increasing self-service, or reducing maintenance.
So, my question to you all is, what are the metrics that would be important to you and your government agency?