Social networking, privacy and investigations

For once, I can stop criticising social networking. Manchester Police force uses Facebook in an innovative way, to promote communication and gather information about crime; http://www.facebook.com/apps/application.php?id=9878600737&ref=s
I wonder how effective it is and if privacy, which is the biggest problem on social networking, can be maintained. I would be curious to see the results of any study made on this matter.
http://www.techdirt.com/articles/20080418/164250892.shtml (21st April 2008)

As an illustration of privacy issues, see this acknowledgment by Facebook that spammers' attacks increased, notably because the users' contact details such as e-mail adresses are available even if the users have not opted for such "transparency". "Facebook admits to increased attacks by spammers" http://news.zdnet.co.uk/security/0,1000000189,39397448,00.htm (22 April 2008)

And this is without counting on the fact that users often do not realise Facebook is about publicity not keeping details private. See this story about a US military who published photographs of his base!! http://www.techdirt.com/articles/20080423/183304931.shtml (23rd April 2008) or those Oxford students the University disciplined after scrolling Facebook postings http://www.techdirt.com/articles/20080504/2148451026.shtml (6 May 2008)

So it's not surprising that the University of Wales launches academic studies of the social networking phenomenon in relation to cyber security http://www.crime-research.org/news/09.05.2008/3355/ (9 May 2008)

Yet the reaction from N-Y to punish those incriminating themselves on YouTube (I agree, it's not social networking in the proper sense- but its audience makes it similar to social networking) is quite surprising . How can such crime deter people to put videos of illegal activities? What is the purpose of such potential legislation? "New York Wants To Punish Criminals For Incriminating Selves On YouTube" (13 May 2008)http://www.techdirt.com/articles/20080512/1802591092.shtml