I've observed in my (admittedly quite short) time here that old answers have an extremely strong advantage over new ones. I'm not really talking about the "fastest gun in the west" problem, in the normal sense of bias toward the first of two answers posted a few minutes apart. I'm talking about age differences measured in months or years.
As a general principle I don't think this bias a bad thing, as it promotes stability and prevents lousy new answers from gaining much visibility (as is the case in wikis, for example).
However, it seems to me that this characteristic of SE sites often causes Age to overpower Quality as the primary determiner of which answer(s) appear at the top -- even when a question has no accepted answer.
Thus, users who contribute high-quality content are incentivized to focus their answering efforts on brand-new questions, rather than providing answers to old questions that have only mediocre answers that have collected upvotes over the course of years. This incentive means that old, highly visible questions that could stand to see some improvement are not likely to get it.
In the interest of promoting the overall quality of the site, thus, I'd like to recommend that everyone recognize the efforts of those contributing high-quality content to old questions: these users usually earn little rep for their contributions, relative to their quality. I'm sure there are a number of ways this recognition can be given, and I'm open to suggestions.