A few days ago, Facebook quietly changed their friend rejection procedure. Instead of opting to Ignore, you can now only defer the put-down by clicking Not Now. But those purgatoried people can still read all your public info and updates.
As TechCrunch observes, when someone sends you a Friend request they get immediate access to the information that you've designated as available to Everyone in your privacy settings. Once they're rejected, they're blocked for good. But by creating this friendship limbo, Facebook is creating a Twittteresque follow feature.
You can still deny friend requests outright; it just takes an extra step. Once you've said Not Now to a request, you're asked "Don't you know ______?," and if you say no they'll be blocked. If you don't say no right then, you have to head to your Requests page to block them.
With any luck, you've already made your privacy settings strict enough that this won't be an issue for you. But that's not who this policy change is targeting; Facebook's banking that if you're lazy, uninformed, or exhibitionist enough leave your info exposed to the world, you'll be equally so when dealing with friend requests.