WikiAlong is a new extension for Firefox that’s so cool, I may need to go lay down for a while. Basically, it puts a Wiki page in the browser sidebar, and displays a Wiki entry for every page you visit with the browser.
Wikalong is a FirefoxExtension that embeds a wiki in the SideBar of your browser, indexed off the url of your current page. It is probably most simply described as a wiki-margin for the internet.
One general difference in the functioning of the wiki you may find is that wiki links would be external, as opposed to traditional wikis which are more internal link centric.
By default, it links out to a central WikiAlong wiki, where people post notes and comments about random sites on the net. I think the real use for this, though, would be a content or design team collaborating on a web site using a private wiki. You could trade running commentary on the design, then flip over to the Web Developer Extension, and edit your CSS on the fly. I wish Firefox was a physical object of some kind, so I could hug it.