Each of us is reponsible for negotiating his or her own salary for a position. Often we don't have much leverage to exact a higher salary, and even if it's deserved, so many companies don't have the flexibility for managers to pay higher salaries than what is set in some range by their HR group. That's discussed a bit in this post from Chris Shaw that looks at hiring and salaries.
I've always felt that the way we handle salary was developed by owners and managers, and the process benefits them, not the employees. We rarely discuss salaries at work, with disclosure sometimes forbidden. Your salary adjustments over time seem to be highly based on your current salary. That means that your starting salary often determines your future salaries at a company, regardless of your abilities relative to others or the market. Even changes in supply and demand may not affect your salary.
A few companies have set salary ranges publicly within the company and some even disclose salaries among employees. It sounds strange to many of us, but I've talked with a few people that work in those environments and it's not a big deal. You earn your salary or you don't, and if you do a good job, no one complains. If you don't do a good job, then many of these companies are quicker than most to ask you to take a pay cut or leave. Personally, I like that type of environment.
I doubt we'll have open disclosure going forward, but fortunately many of us have the ability to change employers easily with our skills if the markets change and we feel we're underpaid. The flip side is that there can be competition for your job and companies might find it easier to let you go and choose someone else that provides the company a better value.
The only advice I would give most people looking to negotiate salary these days is that you should ask for what you're worth, even if it seems high to you. The worst thing that usually happens is the employer says no and offers you a lesser amount. However, if you don't ask, you won't get the salary you want.