I was grepping through the Windows binaries looking to see from where messages come when I ran across a little surprise. The Eye-Fi manager software uses a piece of free software called curl. Specifically, they statically link in a library portion of curl, libcurl. It basically implements a little tiny web browser inside of their application so it can talk back to the Eye-Fi web servers.
It is a bit of a shame that Eye-Fi would choose to use free software inside of its products, but neglect Free Software users by not providing specs or software that run on Free operating systems.
By the way, nobody is violating any license or legal terms here. Curl is free to use in the way Eye-Fi uses it. I just don't think it is very nice.