Upon installing Mavericks, and turning on iCloud keychain, I noticed that all wifi networks I had ever connected to appeared in the preferred network list on my Macbook.
There were quite a few I naturally wanted to delete, so I removed them. Also my devices were trying to connect to networks I thought I had removed.
It didn't take me long to notice that my Macbook was trying to connect to some of these old networks again, and upon looking at the list - all deleted entries had reappeared.
Another symptom seems to be that if I tell my iPhone not to auto-connect to a public hotspot (BT WIFI for example), if my Mac ever comes near that hotspot it auto connects - as will my iPhone subsequently.
I have tried editing the com.apple.airport.preferences.plist file manually, deleting the Mac's WiFi service and recreating, and resetting network settings on all my Apple devices.
I have even looked at the Keychain app on my Mac, but it doesn't seem to be storing my wireless networks from what I can see.
From my Google-ing, it doesn't sound like anyone else is having this issue..
For the benefit of anyone who happens across this article, I may have found a solution.
It looks like the local keychain may be conflicting with the iCloud one. If this is the case though, no amount of editing/repairing the keychain resolved it for me.
To that end, I logged out of iCloud in settings, then logged into another profile (an Admin) and deleted my user account - retaining the Home folder in its current location (I navigated to the home folder and renamed it to remove 'deleted' from the end to facilitate the next step).
I then recreated my profile, and pointed it to the retained Home folder from my old profile. Note that the home folder and profile name must match.
When I logged in, everything was exactly as I had left it - I logged back into iCloud, and was up and running in minutes. All the caches and keychains from the old profile seem to have been deleted, but if you use iCloud keychain, it will all restore properly.
The whole process took about 10 minutes, and the network error has not come back in the last 5 days.