Facebook has just posted an update to its S-1, disclosing a new threatening letter it has received from Yahoo. Yahoo is warning of 16 more patents that it believes Facebook may be infringing on.

From the filing:

…we received a letter dated April 23, 2012 from Yahoo indicating that they believe 16 patents they claim to hold “may be relevant” to open source technology they allege is being used in our data centers and servers.  Yahoo has not threatened orinitiated litigation with respect to matters described in this letter but it may do so in the future.

The first batch of patents were about Web technologies, these are about Web infrastructure, server design, cooling technologies, and a lot of the open source software that run this infrastructure. Yep, not satisfied with taking on Facebook, Yahoo (pictured above, rear) is now taking on the open source movement (pictured above, front).

The technologies in question include things like memcached which was created in 2003 by LiveJournal and has been used longer than Facebook has been alive. It is also used by companies like Wikipedia, YouTube, Reddit, Zynga, Twitter, and countless smaller companies.

Other examples include Open Compute, an open hardware project started by Facebook that focuses on low-cost, energy efficient server and data center hardware; Tornado a Python-based web server used for building real-time Web services; and HPHP, a source code transformer that turns PHP into C++.

The message from Yahoo: We own the Web and everything powering it.

The statement from Facebook continues its stance of being the defender of the Web with no signal that it intends to settle:

Yahoo’s letter takes aim not just at Facebook but at open source and energy-efficient green technologies developed and employed by countless innovative, forward-thinking companies and engineers. We’re defending vigorously against Yahoo’s current lawsuit, and would likewise do so against any new assertion.

I don’t really know what more there is to say about Yahoo’s patent trolling that we haven’t said already. But it’s impressive they keep finding new lows.