Re: Estoppel vs. Laches in the USA
First off, I'd like to preface this by saying that not only am I not an attorney, but IP law is one of the more byzantine areas of US law. This is my understanding after being exposed in bits and pieces over the years, and doing a little bit of research on my own. But you should consider this to be more than the usual IANAL disclaimer. Most of what I'm seeing on the net on this topic, including my own posts, even including what I'm seeing written by journalists, is clearly being written by people who don't have a firm grasp on the topic, and some of the worst offenders are from those that think they do. So, you have been warned.
As far as I am aware, there is a significant limitation to a simple patent "delay" defense under US case law. That is, if a patent holder becomes aware of an infringement of their patents and does not enforce their patents for a particularly long time (6 years seems to be the standard?), the patent holders ability to persue damages for infringement prior to their actual attempt to enforce their patent may be at risk (mainly, the defendant has to think to ASK for the shield). However, this does NOT prevent the patent holder from seeking injunctions preventing further infringements in the future. This is still not a winning solution for the OSS crowd (or, honestly, anyone else) should patent suits start flying.
In contrast, should the patent holder begin to enforce their patents, such as with a cease and desist letter, and then drop or fail to follow up on their claim, after a reasonable period of time the alledgedly infringing party may reasonably consider the matter to be closed. Should the patent holder attempt to persue the matter again at a later date, they (the defendant) may request that the court have the plaintiff estopped, that is, completely barred from enforcing that patent against them.
Finally, re: USA vs. the Rest of the World.... yes, yes, yes - you are all right (well, as far as /I/ know). These patents are worthless in the more sane portions of the world. But look who the major players are. Microsoft. Redhat. Novell. IBM. Sun (if only, in this particular case, for OpenOffice). A few hundred unnamed Fortune 500s. This fight, if it makes it to the courts (which I for one doubt it will, actually) will take place in the US court system. Let me make myself clear here - I don't support the gross overreaching that the US has done in recent years. In this case, however, whatever lawsuits are filed (if any) will almost certainly be with both parties in the US, so it's going to be under US jurisdiction, and we're going to have to deal with US law - even if it is fundamentally broken when it comes to software patents.
-Daniel B.