These aren't necessarily individual roles - one person may do more than one to start with, and as the event approaches these roles will split into several roles or even committees. What they represent is more independent "streams" that may be tackled fairly independently.
The venue manager deals with everything to do with the venue that isn't the actual content of the conference - they provide suitable surroundings for a conference to occur. This is rooms, catering, furniture, layout and design.
Get detailed description of assets: what rooms do we have, when, for how long, how are they staffed?
Catering
Fix requirements - amount, frequency and also dietary requirements
Negotiate with caterers
Signage
Childcare
Foyer design
The foyer at the Barbican is massive and will have lots of activities in it.
Wikimania London shall be a global outreach event, with a reach far beyond London. We shall recruit volunteers from all around the world who are passionate about the movement and are active within their local communities and arm them with pre-assembled media packs and a dedicated section on the Wikimania London website, with a mission to engage press within their local countries to cover Wikimania in London and provide a clear call to action for anyone who may be inspired by the events of the conference. These may include volunteering with their local chapter, joining / organising events in their local community, or just simply how to edit Wikipedia.
Coordinating with Local Press / Local Chapter / Local Wikimeets to garner increased interest in to local wikmedian projects
Good copywriting skills to adapt press releases for the local territory
Keep community updated on everything that's happening, Including accommodation details, visa process etc... basically everything all the roles are doing
Similar to the London 2012 games makers, Wikimania 2014 will have a team of volunteers for the duration of the conference to help execute the event and assist attendees.
The bid committee will be presenting at the annual WikiConference UK in Lincoln later this year to attract volunteers.
As part of our Legacy initiative (see legacy tab), we'll invite members of teams bidding to host Wikimania 2015 to lurk our mailing lists and once the location for Wikimania 2015 is confirmed, we'll invite members of that organising committee to work closely with us in the run up to the event.
If you are interested in volunteering, email infowikimanialondon.org with your name, what you'd be interested in doing and why you think you would be awesome at that particular job! We will be recruiting certain roles from the international wikimedia community - these will be promoted closer to the time.