I think Flicker showed there was a real pent up demand for exactly what you are talking about. Google has tried to step in with Picasaweb. It's good software, but will never have the social aspect that Flicker does. I think that's why Google paid so much for youtube. They didn't want to be left behind on the social aspect of video too.

Without knowing Facebook very well, it seems like the ideal thing for what you're trying to accomplish. Plus, it has the advantage that many in your target audience are likely comfortable in it.

Or, you could check into blogging software. You can put up posts, and others can comment on them. You might even be able to have multiple people have the rights to put up posts. Here's the Wikipedia page for a starting point. You would want developer hosted software such as Wordpress or Blogger (Google's service).