Yes! You do need to market the service desk.Why?
If you have external customers, then the answer is clear, increasing customer numbers is your business, and you want to stay in business.
If you have internal customers, then you need to get a clear message out there about the value you are adding to the business, so you are not just seen as a "cost centre" (and I truly do think service desks can add great value!).
Who?
External customers are easy to identify, who to market to for internal customers may be a little harder. You need to ensure end users are aware of the service you offer, and the value you provide, as they are the ones who will call, and they will tell their managers if you are doing a good job or not. You need to especially market to senior management, they guys who actually pay the bills. They are the ones who mostly need to understand what they are getting for their money, and the value you are providing, make it clear!
When?
Always. Why stop? Make sure you get your message out, and it is targeted at the right groups, and do it often (but please no spam).
