Edit (04-Apr-2017) I have since deactivated my Facebook account for the time being but I shall leave this blog post active as I still believe the post is fair reflection on the subject
I read a blog a few months ago by Ramkumar Gopal (blog) in which he had setup a Facebook page to record and post things that he doesn't want to create a blog post for. I thought this was a really good idea for a whole host of reasons, so much so I went ahead and setup a community Facebook page for myself as well.
My blog, like many others, is syndicated to a couple of large SQL server sites so I'm quite careful with my blogging. I only blog once or twice a month (too busy to blog anymore!) and I'm very meticulous with the articles that I post, or at least I try to be! There are times where I want to post something publicly or share my thoughts or just record something that I've just done, but not have that syndicated to 1000's of fellow blog readers via the syndications. I've noticed that over recent months the number of new blog posts on the sites that I follow has increased quite substantially. This is great of course for the community, but it does mean a lot more to read or skip over. I don't want to add any more white noise to the blogging community by posting tiny one line articles that are more suited for Twitter rather than a blog. For me a blog should be something that people would find interesting to read today and even in the months & years ahead.
Career wise, your blog is an incredibly powerful alternative CV and I believe to reach the higher echelons in any IT field a blog is becoming essential in helping you achieve that. It will show any potential employer or client exactly what skills you have and the level of those skills. It also demonstrates that you enjoy feeding back to the very same community that feeds you. Not all of us are geared up to give talks and do training/demos etc, (I'm most definitely one of those!) so blogging what you know is a perfect way for giving up a little of your free time for the community.
Another reason why I think it is a good idea to setup a community page on Facebook is to reserve your brand name. As time goes on, it will get harder and harder to get the username/URLs that you want. Getting in now, setting up your page and reserving that all important public Facebook URL is pretty important if you have a brand name that you want to use more in the future. It's a bit like the domain name registration rush I suppose back in the late 90's (or indeed when any new TLD comes out)
Having a Facebook community page also allows me to totally isolate my professional and personal life. I can now publically advertise my SQL server Facebook page URL on my website quite happily and keep my personal Facebook page exactly that, personal. I don't need to bore my family and friends with latest news regarding Hekaton or how great I think Brent Ozar or Paul Randall is etc and likewise my SQL friends don't get bored seeing pics of me with my family or pics of me drunk or just generally being stupid.
You could argue that some of this I could do with Twitter. You're right, I could tweet my thoughts and share new links that I find but to be honest, I don't fully get Twitter. I sort of understand why it is great and why some people can't put it down, but it just doesn't seem to suit me. It seems to be more about the moment. Sure I have an account, but I don't tweet anymore. I used to follow a few people and read their tweets, but something just never clicked for me. As such, I just slowly stopped reading until I wasn't reading at all. I think I prefer more meat on things I read. Maybe why I prefer to read blogs and whitepapers/books over Twitter.
My SqlServerRocks Facebook page hasn't been up for long so there isn't a huge amount of content on there yet, but it would be great if you popped by and liked it sometime.. I will be putting updates and content on there more regularly than I blog.