Although Flock has some nice features for integrating your social networks and media, it also has some very significant drawbacks. It always lags behind the current Firefox version for security updates & other fixes, and bookmarks work very differently (which I personally dislike).
Yoono is a Firefox plugin that gives you the best of both worlds. It adds a sidebar which provides much of Flock’s more useful functionality. Combined with Scribefire for blogging, you can have most of Flock’s functionality with a more mature & well supported Firefox browser.