Through a link on Nathan Bransford's blog, I came across this article ("A Right Fit": Navigating the World of Literary Agents) which is pretty much exactly what it sounds like. If you're interested in the publishing business at all, it's worth reading, but I wouldn't say that I agree with the writer's conclusions. His main conclusion is that getting an agent is all about who you know. Recommendations from author-friends, going to conferences, etc.
From a personal standpoint, I've heard this bit of "advice" far, far too many times. It's a fairly prevalent thought, that the best way to get noticed by a literary agent is to be recommended by one of their clients or to meet them at a conference. And I know that stuff works; I know there are authors who met their agent at a conference or were friends with one of the agent's clients or maybe had some other "in." But when I was querying, I started to hear this so often that it felt like the only way was to have some sort of inside track. The fact that I didn't go to conferences (I went to one, years ago, and it was awesome, but I haven't made a habit of it since then) and had nobody recommending me to an agent drove me, admittedly, a little batty for a while. If my publishing future depended on me meeting someone at a conference or getting that all-important recommendation, it might never happen.
How I eventually did get an agent was entirely through the slushpile. I sent a query.
I know that connections can help, probably help tremendously in some cases. But I don't believe for a second that it's all about who you know. I think it's about a variety of things: what you're writing, how well you're writing, who you query, timing. And honestly, for those who aren't already surrounded by those in publishing, who can't make it to conferences, who aren't in "the club," as the article puts it, the idea that getting an agent depends so much on who you know can really wreck you.
Knowing people can be helpful. Writing well, researching agents, and being determined can be worlds more helpful though.