First impression is very positive. Besides the fact that as Italian I am really proud of the work, I truly believe that the ideas presented are revolutionary.
The old idea of searching a website is definitely over! Search for content enriched with social interactions. You can see the same website from different point of wiev (map of the site, folder view of the multimedia content and so on). The Volunia engine seems to be able to abstract from the website structure to get to the "met": the content and being able also to integrate the social aspect to every element of the site.
During your visit to a website you can see who is visiting the same site as well and maybe ask for his/her friendship; here in case of websites that are massively visited, the social aspect may be a bit useless, but it makes a nice parallel with real life... imagine going in time square in new york where lots of people are. But in case of websites highly specialized it is easy to make friends with people with the same interests even in case we never met.
Possibility to track friends navigation is also impressive, but people does not always want to be "tracked". However i believe this issue already came out in the Volunia team.
First impression is very good.. i am waiting for my account to be activated!!!