For certain files that I copy from one of my drives to the NAS here (Synology 206j), ever since upgrading to Snow Leopard, Finder's behaviour has changed. It will simply refuse to copy the file, stating that "The operation can’t be completed because you don’t have permission to access some of the items."
The source is an external USB drive in Mac OS Extended format, I do have full permissions on the files and in any case the drive is set to ignore ownership.
The target is, like most NASes, in EXT3 format. It's sharing via its own AFP implementation.
I'd have tried repairing permissions, but for whatever reason, it's greyed out on my external drives. Since then I've figured that it was probably not that anyway, which will become apparent:
I tried copying the file via the terminal and it actually worked, but also gave an error: "cp: myfile: could not copy extended attributes to /Volumes/media backup/myfile: Operation not permitted"
This suggests to me that, as expected, the target volume doesn't support extended attributes. But rather than popping up with the message that Leopard did (something along the lines of "your target volume doesn't support extended attributes so your file's metadata may be lost, do you wish to continue") it just aborts instead.
I'm not sure if this is a Snow Leopard problem or a change that Synology need to catch up with. A workaround is to compress the file to ZIP first.
Thought I'd mention it here before trying to report it as a bug somewhere. Anyone else having similar issues, either with a NAS or some other storage, in which case please specify?