privacy and focused discussion on a area of interest are such obvious characteristics of standalone social networking vs. Facebook. I have the thought it might make more sense to be comparing use of jomsocial to a forum or bulletin board interface. Because of the use we are putting it to. Most of us have Facebook accounts and will continue to use them to share things like a child's birthday party pictures with family and friends that we wouldn't think of putting here. Personally I like the social networking interface better and never liked the forum interface but it might offer advantages if you get a very large number of users and topics. Those of you who are more knowledgeable about forums please enlighten me if I am missing something about the big difference between the two

I agree with Miles...and most of the other comments as well. Facebook is a little like doing Christmast cards for me...I like sending out a greeting to lots of people I don't see very often and I love getting a little something back about what those people are up to but I can't keep that kind of communication up with so many on an everyday basis. So, I log on, feel a bit obligated to make comments, etc and I feel good after I do it but it is not something I'm drawn to do as often as I should.
Now, JChicago is already different for me. Like others have said, by the nature of the site, most if not all info is going to be of interest me and since we only get to meet once a month and usually briefly at that, this is a great way to get to know people better and learn more. That said, I still feel like I'm fumbling a bit with JomSocial...a bit clunky or something.

I think a stand alone will weed out "Friends" that have nothing to do with your networking objectives. We are all interested in Joomla and or CMS websites. I think you get a cleaner networking group.

Basically, stand alone social networking lets you focus content more narrowly than the catch all sites. This has several benefits to the end user.

1) one of the annoying things about facebook/linkedin/etc is that we're regularly subjected to our friends' news in uninteresting topics. I'll leave out the ones that bug me but I'm sure we each have people in our social circles that update with less than inspiring content.

With sites like joomlachicago.com that have a fairly specific goal in mind, I don't have to worry about someone posting something uninteresting to me. The site by its very nature guarantees relevant content.

2) Having a social networking site allows you to make the rules. Like kevin said, you may want to shape the site to accommodate a particular audience. Stand alone can let you do that.

3) While the big boys bring you together with the idea that you have existing friendship connections, having a stand alone site can bring strangers together by virtue of a common interest. I know, it's internet 101 but it's true. I wouldn't have met or spoken to anyone here if I hadn't searched out joomla chicago in google. now, here i am!

conclusion: I think the make-or-break factor for standalone social networking sites is how well they integrate with the big boys. I'm very impressed with plaxo for how well it harvests all of your social networking activity on other sites and brings it to your plaxo profile page. If I can post on joomlachicago and have an option to "share on twitter", I think stand alone Social networking has a fighting chance.

Control:
Limited or controlled advertising.
Ownership.
Look and feel.

I'm working on installing jom social into my site once it's built out. It's a boy scout site. As a leader, I don't prefer to have my private life moments (me drinking beer with my band) show up in front of my scout kids. Plus I would like to interact with them in a focused envioronment without ads. The site is trying to foster a community idea, and I think having a networking component will help that.

I'm looking forward to having much more event information available than the regular features of joomla. In regard to safety issues, we don't like publicizing when a bunch of youth are having an activity...

Also, we are working on alumni connections - and I think this will only help that. Facebook is great - but it's so public. I don't want kids to feel like they have to hide their scouting - depsite it not being something to not be proud of...

That's my take.