I just found out about, downloaded and am writing to you from within Flock, a Firefox-based browser released today as a developer preview (i.e. potentially buggy but functional) version for Windows/Mac/Linux. I’ve only been playing for a few minutes, but thus far I’m impressed, especially with the built-in blogging tools. Flock has a built-in system for browsing through your Flickr account while blogging and something called “The Shelf,” a separate popup window where you can drag and drop images and/or highlighted text for use later in blog posts (a great idea for those of us who keep multiple browser tabs open while surfing and/or blogging). The browser also eschews traditional bookmarks (based locally) in favor of online, shareable bookmarks made possible by del.icio.us.
Flock also has a built-in RSS reader, which at the moment appears to work perfectly well with LIVEdigitally and NYTimes.com but is stumbling a bit with Engadget. Like Firefox, Flock supports extensions like Greasemonkey and AdBlock.
Take a look at this news.com article for more info. Vive le open source movement!