ARGs : Where do you draw the line?

Alternate Reality Games (ARGs) and the whole idea of viral marketing (wikipedia links) are becoming quite popular lately with the success of things like Halo 2's ILoveBees and Burger King's subservient chicken.

The whole idea of ARGs is to blur the lines between games and reality by creating a story that appears to be real and that people can get immersed in. I have been following the Perplex City ARG lately (although the idea of buying 'puzzle cards' is putting me off).

This brings up interesting questions of how far companies can go in making their reality appear real.;
BoingBoing is reporting a story involving a new ARG set up by the BBC. It looks as if people from the BBC have intentionally set up pages on wikipedia about a character and group that only exist within the ARG.

As the whole point of wikipedia is to provide an online encyclopedia, for its credibility it is inportant for the articles to be true. Therefore, I think if the reports are true, and the BBC have created these pages, then they've crossed the line!

This gives an interesting question with everything on the web, which is only being highlighted by ARGs deliberately creating false information:

How do you know what you can believe out of all the information you read online?

I cant see an easy solution to this problem....