Rob - I launched the Emap specialist sites a couple of years back, including social networking and user content facilities. Very happy to talk through some of the learning with you. You might find my article on encouraging user content helpful:
http://www.penmaen-media.co.uk/index.php/2009/01/five-ideas-for-user-content-on-your-website/ Send me an email via the website :
http://www.penmaen-media.co.uk/index.php/contact-us/ and I'll give you a call.
Carolyn Morgan
Penmaen Media
www.penmaen-media.co.uk