The rise of social networking sites and citizen journalism has been a wonderful  breath of fresh air, connecting people and ideas as well as shifting the balance of power away from established institutions back to individuals whose voices are now more likely to be heard

But despite this wave of optimism there is always something unsavoury lurking in the background which militates against complacency.

Two stories came to my attention today which demonstrate the nature of these threats and how they range from the slightly subversive to the blatantly sinister.

In the ‘slightly subversive’ camp we have the actions of individuals and groups seeking to ‘game’ social media sites such as Digg, Newsvine and Netscape.

This is covered by Charles Arthur of the Guardian today who reports that Digg founder Kevin Rose has announced an impending update to its algorithms to prevent groups from distorting its democratic model.

Not before time.

People can argue that the groups helping each other or backing a particular cause cancel each other out in the end but the reality is that these sites will lose their credibility if the editorial voice of the people is not really the voice of the people.

(On a similar theme there are question marks about whether these sites should be paying their top contributors but, again, the extent to which this is distorting their ‘higher purpose’ is open to debate.)

What isn’t open to debate is the need for online social networks such as Bebo and MySpace to clamp down on the sinister manipulation of their sites for abuse and exploitation.

A study by Computing Which?, reported by the BBC, says (unsurprisingly) that the networking sites should do more to police what users do in order to protect their users (from adults pretending to be children, for example).

The likes of Bebo and MySpace have a major challenge on their hands to make their sites as safe as possible.