In the wake of 9/11 there was an enormous shift in the way that counterterrorism intelligence was shared. No threat goes unreported now and intelligence goes to the maximum number of potential consumers because nobody wants to be blamed for a second 9/11; for having the piece of information about the guy who wanted to learn how to take off in an aeroplane but not how to land it.
But the Afghanistan leak is likely to lead to more controls to prevent self-proclaimed whistleblowers from gaining access to this kind of information. Things are unlikely to revert entirely to the way they were, but there will be an effort to groom distribution lists and to monitor consumers. WikiLeaks may find themselves having made such leaks less, rather than more, likely in the future.
The second big ramification will be with friends and allies of the United States, particularly the Pakistanis, who are going to look at this and say: "We may be duplicitous, but at least we can keep a secret."
On the ground in Afghanistan, the story is likely to be widely spread that if you tell the Americans anything, it will show up on a computer somewhere with your name on it and the Taliban can come after you. That's going to have a chilling effect on intelligence gathering in Afghanistan. It will make very tough intelligence channels even more difficult. It may also lead to less sharing with allies.
Once you begin to protect the dissemination list, the first to fall off are foreigners. That makes the Afghan situation even more difficult for the 40 countries with troops on the ground.
Intelligence sharing is absolutely critical, but if there are doubts as to who can keep a secret, there will be pressure to pool information more closely. The torture of detainees, the secret prison camps and the whole litany of assaults on civil liberties which followed 9/11 brought a predictable public backlash.
People now don't trust their governments' handling of the whole "war on terror" and want to put a spotlight on intelligence communities which they think are out of control.
That is understandable given the abuses that have taken place, but it's still not for individuals to decide on their own that they should be the ultimate declassifiers of secret information.