I'm getting the same networkmanager warning (connecting via wifi) on RC4
Aug 31 23:52:18 slacker64 NetworkManager: <warn> Failed to open plugin directory /usr/lib/NetworkManager: Error opening directory '/usr/lib/NetworkManager': No such file or directory
The 'link cache' warning appears also, but this might just be a networkmanager "feature" - not sure though.
I got rid of bluetooth warning/errors by disabling and blacklisting: as this laptop does not have BT capability, but does have chipset support for the [not present] add-on device, the kernel and KDE kept trying to find a nonexisting BT device. Although networkmanager, the idiot that it is, keeps looking for bluez.
I don't get the "org.freedesktop.NetworkManager.wifi.share.open" warning.
I think, though, that I will dump networkmanager for WICD until it matures a bit more. I don't need any of its fandangled features anyway.