I wasn't able to get copy/paste working via keyboard shortcut (command-C/command-V on the host and shift-control-C/shift-control-V on Linux), but the copy/paste keys were working when copy/pasting within the guest. For example, I was able to copy text from my Linux terminal using shift-control-C and then paste it into another window on the Linux guest via shift-control-V, but when I pasted into a window on the host using command-V, all I got was the contents of my host pasteboard, rather than the text that I had copied on the Linux guest.