(This commentary is occasioned by the announcement from the OLPC project April 28 that Microsoft Windows will be put on the XO Laptop, that the price will rise to $175 and that the minimum order quantity will be reduced. See OLPC News for further details and history. See here for my initial post on OLPC.)
So, let's say you've got a dysfunctional society and things have to change but nothing is forthcoming from the top. A charismatic leader turns up and convinces a lot of people to help him build a new order with or without the permission of the rulers. Enough people join in and coordinate their work so that things can be done the way everyone agrees they ought to be done and not how they are done.
Eventually this comes to a point of confrontation with the rulers and, surprisingly, they clear out, leaving nothing behind. Your group fills this power vacuum and everything seems to be going great. Your charismatic leader has good political connections with the outside world, and you trust him to set things up right. You've had a peaceful revolution!
Then, with no warning, an invading army appears and begins a march on the capital city.