Microsoft stopped developing Explorer because with Jaguar, Apple did the same thing with Web Services that Microsoft had been doing for years: built it into the OS. Explorer for Windows is an app which reuses mostly OS-level services including HTML rendering. So is Jaguar. Notice that both Apple and Microsoft ditched proprietary help file formats for HTML-based ones? iTunes 2 now has an entire browser of its own for surfing the iTunes store. Explorer for Mac requires either continuing to reinvent the wheel and build your own product on it, or reuse Apple's services which means essentially Jaguar with another name. I don't blame Microsoft for getting out of the way on this matter and letting Apple do the same thing they did. Adobe's choices are a little stupider, but they're having to compete with an application written by the OS's developers (the same edge Microsoft got roasted by the DOJ for). Note that they're keeping all the other graphics apps in a current life cycle, markets Apple has no interest in.