A Firefox extension for Performancing was released by Nick Wilson and his team yesterday (December 20, 2005) according to this post on the Performancing Blog. Performancing is a browser based product that allows you to post to an existing weblog via the browser. This is very similar to a feature that the "social browser" Flock had released however based on some of the comments and posts I have read in the blogosphere it appears that Performancing offers more ease of use then the Flock feature. So basically, you download and install the Firefox extension to your Firefox browser. Next you can configure your existing weblog. Finally, any time you see something on the web while surfing using Firefox you can right click your mouse anywhere within the browser to open a blogging text editor and beginning posting to your blog instantly. I had to update my Firefox browser first before installing the new extension. Also I had to uninstall a few other extensions due to some issues I encountered.
You can download the extension here. Additionally, Steve Rubel and Darren Rowse give their review and perspective on the new extension.