There is still some protection, though. If I were a patent troll and found some patents that might be applicable to h264, it might be a better idea to sign up with MPEG LA and get a cut of the existing pie than to go after MS or Apple for a bigger slice.

The patent holder can also decide not to bother MS/Apple/etc, and only prosecute open source implementations.

The patent holder could be bought by MS/Apple/etc

Unlike copyright there is no requirement to assiduously defend a patent.

You're thinking of trademarks, not copyright.

Yes sorry, however the point remains.

It's perfectly legitimate (and common) for a patent holder to sue a single strategic competitor while leaving a larger player alone.

An impartial (commercial) industry body could decide to sue only FOSS implementations in order to keep the field open for their members.

You can't sue FOSS authors for infringing patents (source code) -- you can only sue the distributors of executable implementations (binaries)

The text of an ideal software patent is (or has a direct mapping to) the source code of an implementation, just as an ideal steam engine patent would be blueprints and schematics. The text of patents must always be publicly available to be enforceable -- it's the whole point, absolutely central to "the promotion of the useful arts and sciences".

You license the production of artifacts, not the spread of ideas.

It's called contributory infringement.

If I supply you with tailored parts necessary to perform/make a patented invention then that's contributory infringement.

In the US Findlaw says:

"Contributory infringement occurs when a party supplies a direct infringer with a part that has no substantial non-infringing use. Literal infringement exists if there is a direct correspondence between the words in the patent claims and the infringing device."

http://smallbusiness.findlaw.com/patent/enforce-patent/paten...

You could argue that the source code is an implementation.

Anyway the point is rather irrelevent, you aren't going to sue anonymous contributer100. You are going to sue, or threaten to sue, companies who propose using opensource platforms for their new website rather than buying from one of your members.