Help me help you help yourself
Like it or not, there will always be informal knowledge sharing between users in a given work area. Some users have encountered a particular error before and help their peers resolve it. Others feel they have (justified or not) enough experience "with computers" to help themselves or others troubleshoot whatever issue they are having. This concept can (and often does) illicit fear in the hearts of many experienced sysadmins.
Trusting users to be able to seek out resources (internal or external) to solve the problems they face is a difficult thing to ask of many IT personnel. Anyone who has come up through the ranks has had to earn their stripes on a help desk somewhere. That help desk experience can be dehumanizing, not only for the help desk staff member, but for the users as well. We, as IT personnel have to bear in mind that the calls we get at the help desk, (at least those we remember years later), are not truly representative of our user base. There are usually simply the worst case. Experience unjaded by cynicism will show that in fact many users really are smart enough to solve basic problems.
As a systems administrator, I am the first to admit that my job simply wouldn’t be doable without access to the internet. From search engines to newsgroups, forums and even El Reg, I spend a large part of my day looking up solutions to the various problems that are brought to my attention. Formalizing the exchange of knowledge that already takes place between users in their "natural habitat", thus providing a knowledge base of common errors (and their solutions) is beneficial to everyone involved. Not only can junior IT staff make use of this while “learning the ropes,” but many of these already-solved issues can be taken care of within the group structure that already exists amongst your users.
Not everyone will take advantage of this resource, but you can rest assured that in a given group of users everyone knows who the one person is that actually will. Properly implemented, it is often true that users will find a great benefit in formalized "knowledge bases," and that they might even have wisdom to contribute. While I would not be open to giving my users the ability to blindly edit (read: delete information put there by IT) a knowledge-base wiki, something where the contributions are vetted for accuracy holds a great deal of promise.
I seriously doubt IT will ever fully be able to rid itself of the need for a helpdesk. We can however increase our interaction with the users in constructive ways, relieving some of the burden of problem solving from the tired and weary IT staff. This leaves more time for planning, preventative maintenance, and of course, El Reg and beer.