In a nutshell, you download a little application (both XP and OSX are supported!) onto the machine that contains files or folders you’d like to “share.” In this case “share” just means that you can literally share folders or files with other people, or you can just keep it to yourself and get to your home machine from work, for instance, or vice versa.
I just installed it on an XP machine, then went downstairs and used my Mac to browse and download files on my XP machine. Sweet! This definitely looks like a keeper.