There's a war in progress, and the outcome of it will affect the future of computing. It's important to see it for what it is, so you can prepare for the consequences. The consequences (unless there's a cease-fire in the meantime) will be enormous.
To get a handle on it requires a certain appreciation for the importance of operating systems. Let's back up the truck for a minute and talk about operating systems, and Windows in particular (two different things, really).
Non-technical computer users can be forgiven, I think, for misusing the term "Operating System" in the context of Windows. Underneath Windows is an operating system, to be sure, but the collection of applications that, in the aggregate, gives Windows its Windowsness has little to do with operating systems. An operating system is really about the core-essential software that discovers and registers "devices," controls the bootstrapping of a machine's services at boot time, and provides various hosting services to applications.
From a human user's point of view, that last bit (providing hosting services to apps) is the most important aspect of an operating system. It's what makes it possible for us to run programs and get work done.
But consider what has happened over the past decade or so. The Web has become a central metaphor in computing, not just at the level of desktop PCs but also a variety of handheld (and other) devices. Initially, the Web was a world of static content: You visited a URL with a browser, the browser rendered the page, and you hopped from URL to URL via hypertext links. But now the Web is full of highly interactive "web apps," and the browser is merely an interactive hosting environment for client-server apps in which part of the logic executes locally and part executes on a server somewhere. The browser is now the logical analog of a desktop OS, in many ways -- mooting the importance of something like, say, Windows.
This has worked to Microsoft's disadvantage, obviously. When people rely more and more heavily on a browser to get work done, it tends to marginalize the importance of desktop software; and since the Web is, at its very core, standards-driven (TCP/IP, HTTP, HTML, URLs, etc.; all universally understood standards), the concept of a non-standardized, proprietary OS that doesn't understand how to interoperate with non-native software (or with other OSes) runs counter to a user's needs and actually becomes an anti-feature. When the most important thing a computer OS can do is provide connectivity to an outside world that's based on standards, the proprietary OS is a liability. In fact, the Web makes all OSes equally irrelevant, in some sense, which is one reason Apple is doing well, because the age-old Cupertino stigma of having a non-Windows-interoperable OS is no longer, in fact, a stigma. The field is (almost) level now.
To the degree that things like Windows have become sidelined in importance compared to the virtual OS of the Web+browser, rich Internet-aware (but also desktop-aware) runtime frameworks like Adobe AIR become hugely important. They represent the "next platform." And that necessarily also means the next potentially proprietary platform, because Adobe (to stay with the AIR example) is a closed-source company that still makes most of its money from proprietary, non-open software. Even if you want to make the (hollow) argument that the Flash standard is "open" and uses ActionScript ("open") and XML ("open"), etc., you still have to concede that Adobe has an iron grip over what Flash and Flex consist of, and where they're headed. The only question (let's be frank about this) is whether Adobe is a benevolent dictator or a venal, conniving one.
The battle for the Rich Internet Application platform high ground is really a proprietary platform play: the next big attempt to lock computer users into privately controlled technologies -- technologies like Flash and Flex that could be foundational to future computing. The winner (be it Adobe, Microsoft, or Oracle) will find itself with a great concentration of power in its hands. Which, if we've learned anything at all from history, is a very bad thing indeed.
So before you get too worked up about AIR, Silverlight, or JavaFX, before you drink anybody's Kool-aid and start passing the cup around, remember what you're dealing with. These technologies aren't about making the world more standards-driven or putting more control in the hands of the user. They're about putting control of the Web experience in the hands of a multibillion-dollar closed-source software giant. Choose your poison carefully.
Of course, if one of the big RIA contenders decides to go 100% open-source, and put the future of the platform (whichever one it turns out to be) completely under community governance, then we have nothing to fear; we have a democracy. But don't hold your breath.