The answers above were all assuming your Python distribution would have some third-party libraries in order to achieve the "one liner python ftpd" goal, but that is not the case of what @zio was asking. Also, SimpleHTTPServer involves web broswer for downloading files, it's not quick enough.
Python can't do ftpd by itself, but you can use netcat, nc:
nc is basically a built-in tool from any UNIX-like systems (even embedded systems), so it's perfect for "quick and temporary way to transfer files".
Step 1, on the receiver side, run:
nc -l 12345 | tar -xf -
this will listen on port 12345, waiting for data.
Step 2, on the sender side:
tar -cf - ALL_FILES_YOU_WANT_TO_SEND ... | nc $RECEIVER_IP 12345
You can also put pv in the middle to monitor the progress of transferring:
tar -cf - ALL_FILES_YOU_WANT_TO_SEND ...| pv | nc $RECEIVER_IP 12345
After the transferring is finished, both sides of nc will quit automatically, and job done.