I got 2 happy customers with this technique - let's see if I can get one more:
 Open up a terminal and change directories to the parent folder that contains the Pictures, for example if they are in the Pictures folder of your home directory:
 Now run the following command:
 On the OSX machine open your browser ( I'm talking about your Internet browser not Finder ) and point it to:
python -m SimpleHTTPServer
Change 192.168.0.100 to the ip address of the Ubuntu machine. Note: Since this is a Linux-OSX network you can also use the Avahi/Bonjour naming convention, for example:
As long as you don't happen to have an index.html file in that directory in Ubuntu it should simply list the contents of Pictures. Now you can use the browser to download the files to OSX.
After it's done downloading you can stop the temporary http server on Ubuntu by issuing a Ctrl+C.