The conclusion here is that competition is good for the consumer, and developers aren’t often thought of as consumers.  It’s also interesting that Safari, which lacks Firefox’s robust extension architecture, now has built-in functionality similar to my favorite Firefox extension.  This reminds me of the progression of Mac OS (and perhaps Windows) — imitate popular third party applications, and include them with the OS.  Think of iTunes: MP3 player, CD ripper, podcast manager.  Many popular (free) third party applications have faded into obscurity because people don’t need them anymore.