Hi,
I got the file copying errors too, and the situation is the following:
1. I got a Synology DS-107+ NAS, and I got different shared mapped to my Mac using SMB.
2. I got a Windows XP PC using the same drives.
Before I upgraded to Snow Leopard all was working perfectly on both Windows and Mac using these shares, and to be honest I am unsure if the problems occurred with the SL 10.6 version or with the update to SL 10.6.1. The Windows PC still works perfectly, but when I attempt to copy any file to the shared drives on my Mac I get an error telling me that the action could not be completed as I do not have the rights to one or more of the items. (attempt to translate the Danish message I get to English). In any case it complains about missing rights.
Interestingly enough I am allowed to create a new folder, and delete this folder too, but an attempt to copy any type of file to the new folder or any existing path on the drives fail. There is no doubt it is an error in Snow Leopard, and I just came from the Synology support forum where people reported this error too, and someone referred to this discussion, and here I can see it is a general problem with NAS devices, and not just the Synology boxes.
I sure hope Apple reads through these discussions and takes immediate action (meaning fixing it with highest possible priority). I am new to the Mac side (just 3 1/2 month into my Mac life), but after many years in the Windows world I would say that one point where Apple falls through hard is their ability to send out updates that really screws up things that worked before the update. :/ I hope my future Mac experience will prove me wrong.