I came across this story on Slashdot about Wikipedia which illustrates exactly why it can backfire on itself even with it's relatively good checking mechanisms.
Here is the story:
'Germany has a new minister of economic affairs. Mr. von und zu Guttenberg is descended from an old and noble lineage, so his official name is very long: Karl Theodor Maria Nikolaus Johann Jacob Philipp Franz Joseph Sylvester Freiherr von und zu Guttenberg. When first there were rumors that he would be appointed to the post, someone changed his Wikipedia entry and added the name 'Wilhelm,' so Wikipedia stated his full name as: Karl Theodor Maria Nikolaus Johann Jacob Philipp Wilhelm Franz Joseph Sylvester Freiherr von und zu Guttenberg.'
What resulted from this edit points to a big problem with wikipedia:
Several reputable media outlets started using the wrong name from Wikipedia. Although wikipedia had been corrected it was looking for proof of the correct name. The proof was quickly found on the same newspapers and internet sites which had used the wrong name in the first place.
In short, this is what can happen:
Wikipedia states a false fact, a reputable media outlet copies the false fact, and this outlet is then used as the source to prove the false fact to Wikipedia.
The first problem here is a reputable media outlet getting it's info from wikipedia. But the real issue is that we may have so much info at our fingertips but that info is doomed to be forever flawed with errors. Oh well that is life I guess.