A little more info. The kix32.exe process does not show up in the process list on the computer that is holding the file open on the server.
One office that I checked on the other day, had a number of kix32s open, but now has none. The only thing that has changed is the installation of SP1. Maybe its fixed now. I'll try to do some more confirmation myself, but if anyone else can confirm this, it would be helpful.