I've had to think about this a bit recently, because I'm trying to be a successful published author and one of the things that you have to worry about (if you don't have an agent) is the publishing contract.
There have been some terrible contracts going out recently and I've been trying to get my head around them so that I don't fall prey. The change that has everyone up in arms seems to be that the publisher in question is saying that they will give a larger percentage of sales to the author, but only after variable and fixed costs of production and marketing have been taken out.
Traditionally the publisher is supposed to handle those costs, and many of the larger ones actually own the companies that take care of them, like printing presses.
And fixed costs are less of an issue, because technically, the sales of the book were always going to pay for those. Once they are paid for at the start, that's it. But variable costs are so easily inflated and they will always be there. An author on a contract like this could end up with nothing at all.