[ajross]

In the legal world, that's not meaningless. Simply because one hasn't (yet!) attempted to aggressively assert patents doesn't constitute a defense if one decides to in the future. This might (though it's still not a contract, and I didn't click through to read the terms).

[mindcrime]

Exactly. IANAL, but from what I've heard from people who are, the basic premise behind these kind of pledges is Estoppel[1]. The basic gist of it, as I understand it, is that you can't go around screaming something in public and treating it as the truth ("anybody can use this patent and we won't sue you") and then later come back and contradict that ("you are violating our patent, pay up"). IOW, promises, made publicly like this, do count for something, even if there's no explicit contract.

[1]: http://en.wikipedia.org/wiki/Estoppel