The "world wide web" has been such an amazing success in large part because it was based on open protocols and formats that anyone can implement and use on a level playing field. This opened the way for interoperability on a grand and global scale, and is why http and HTML succeeded where many others failed previously.
Unfortunately, not all areas of computing are as blessed with open protocols and formats. Some are quite significant, too, with hundreds of millions of people using and relying on them every single day. Thankfully, some brave souls have stepped up to implement these proprietary protocols and formats using open technology, specifically as free software. The poster child for this is Samba and the ubiquitous file and print server protocols from Microsoft.
Such formats abound and are a key component in every day business (and personal) computer usage, and since the protocols are often not as open as we'd like it can be tricky to provide free, open and interoperable implementations of them. Again, just ask the Samba team. Yet bringing the option of freedom in technologies used by business and government around the world relies on these efforts.
The free software community is moving rapidly on all fronts of this landscape, and to help ensure that our efforts actually do work as expected and that we are sharing useful information with each other between projects, a fantastic conference has been set up: the Protocol Plugfest which will be held in Zaragoza, Spain on May 12-14. This is much like the ODF Plugfest which focuses on office file formats, but with a stronger focus on protocols found in products such as Active Directory, Exchange, Sharepoint, CIFS and LDAP.