“There’s something quite visceral about moving your avatar to the site you’re discussing”.
Tools around the side allow you to activate pins that pull in news stories from around the web.
Also, there’s a squirrel. It eats (virtual) nuts.
You can browse a Google map of the city centre, and render it in 3D. That wasn’t an automatic process. They did it – took about a day per square kilometre. 
(I suspect that the video above will be more useful than some of my quick notes here.)
All the models, both scale and full are in the open areas right now. In theory, for consultations, you could create locked down versions.
In a public consultation model, you could create “comment balls” where people can leave feedback about the proposals, and even start dialogues with each other about it. 
Doesn’t recommend using Second Life itself for marketing at the moment – the userbase isn’t there, but you can use what you’ve done on webpages.