Mike Riversdale captures this eloquently in his post, "Google Docs ... so what - the ONE reason why you should care"
Wikis live by understanding the connectivity of their environment and the innate desire of 'words' to love all and be loved by all. In the future there will be no difference between a Google Doc and a wiki page ... in fact, it may be so close already it's just a matter of semantics and opinion.
Collapsing the Publishing Process
One of the dynamics of a Wiki is that whatever you create is immediately, or very quickly, published. This means that knowledge can be communicated as quickly as it is captured, significantly outpacing the change in knowledge demand.
To appreciate how dramatic this effect is, consider this example: I recently collaborated with a partner using a Google Docs Spreadsheet. Not only could we see each other's presence on-line and chat using the collaboration window, I could see exactly what cell his cursor was on as he moved around in the spreadsheet, and we could simultaneously update the sheet, immediately seeing all the changes!
Everyone in the Pool
This effect is amplified, by the openness of the environment. Not only does everyone get to see things right away, they get to play! Depending on permissions, like the example above, they can all contribute and increase the value of the knowledge we are sharing.
Staying Out of the Danger Zone
This capability has a downside as well. Having a managed create, review, edit and publish process has its merits. In situations where communication delivery has high impact, it is imperative to balance the risks of misinformation versus the immediacy of publication. However, even in these situations, valuable knowledge assembled in Wikis can be quickly harvested, accelerating the formal processes for delivering sensitive or critical communication.
Image Credit: Wikinomics Blog - Wiki collaboration leads to happiness