TidBITs has a more in-depth report on the bug that causes the Snow Leopard Finder to report error-36 when copying files to shared drives. The article includes some Terminal instructions to work around the problem.
When you plug in an external hard drive that hasn’t been unmounted properly, Snow Leopard actually starts running fsck on it:
/System/Library/Filesystems/hfs.fs/Contents/Resources/../../../../../../sbin/fsck_hfs -y /dev/disk1s2
Of course, nowhere does it actually inform you it’s doing this, unless you hunt down the fsck process.
So what probably happens is you decide it’s not going to mount and yank the cable a couple of times to see if it’s something wrong, of course this just disconnects the drive in the process of the fsck, which is something I’d rather not do.
The Onion have an informative infographic comparing Mac OS X Snow Leopard and Windows 7.