The last entry just listed some of the ways (web sites, rather than your browser bookmarks feature) in which you can keep track of posts from here and any web site you visit. You don’t have to use them. Sorry if the bunnies joke didn’t go over well. :P
Basically a “social bookmarking site” is a place where you can record favorite sites you visit (I’m constantly stumbling on cool stuff from blog links and so forth, and I want to remember them). The links are is stored on a web site, rather than in your browser’s bookmarks, so no matter what computer you are using, they’re all there. When you upgrade computers or (gasp) if your compy dies, the bookmarks will be available to you forever.
Typically you can add keywords or tags to your links so that if you’re looking for a specific one - let’s say recipes - you can click on that tag and bring up all of your bookmarks that have recipes in them. I like this because it’s a finer level of granularity than bookmarking an entire blog (although hey, if you know the blog rocks, why not? :P), so individual posts can be captured.
The other feature of these social bookmarking sites (each of them: StumbleUpon, Digg, Technorati, Google Bookmarks, etc. is basically the same as far as primary functionality) is the ability to share your finds with other people. That’s the social aspect of it.
You can totally still find me with a browser bookmark. :) This was just an option for those who are using some of the social sites to be able to capture posts you like from here and elsewhere and keep track of them in an online format rather than within your browser. I have discovered that it’s way easier to find and categorize sites when I can apply my own tags to them.
Sorry if I caused confusion, and if the joke about making bunnies cry was in bad taste. :P…