Salary Cap: Pros & Cons?

With a rather large standoff expected between the owners and the NHLPA during the hockey offseason, this being over the matter of a proposed salary cap, it got me thinking: what exactly are the pros and cons of having a salary cap? Obviously one of the intended advantages is to give “poorer” markets a chance at the talent, but is there any reason other than greed that the players tend to resist such a proposal?

My question was further stoked on reading that the Yankees are sealing up a deal for Alex Rodriquez. Seems like if any sport could use a workable salary cap it would be baseball, on account of the Yankees alone having enough cash to buy all the talent in the league. On the other hand, the NFL is held up as a paradigm of how a decent salary cap structure should work. And sure, they have achieved a great deal of parity over the last few years. But others would argue that winning the Super Bowl in any given year just isn’t the same in an era which virtually precludes the rise of a franchise dynasty.