What I said a long time ago:
"Concurrent editting doesn't work to great in MiniWiki. It's easy to overwrite somebody else's changes when writing at the same time. For now, next time you come around see if your change is still there. A way of getting around this would be to work on many small pages instead of one big one... see how the simplisity of the Wiki is enforcing the idea of many small digestable chunks of information?"
I said that when using MiniWiki for the first time. However, to date I have had very little problems due to this. Perhaps it's due to not having enough people editting for this to actually be a problem?