Last May, Tim O’Reilly posted a piece on whether or not Adobe was worried about the new threat to their dominance in the RIA space by the introduction of Silverlight from Microsoft. In a nutshell, the answer was no. From a book sales perspective, that was true and remains true today. But there is more to that answer than what appears at face-value from data on book sales.
Silverlight 2 is the product that Microsoft is backing in the RIA race. That in itself is worth, at least, some restless nights. Silverlight has not become a publishing event. At the present time, there are 10 Silverlight books published yet only one is on the current release and is truly a 2 book because it offers free, or paid, updates all the way through to a FCS launch.
But it does appear as though Silverlight is gaining some ground on Adobe. At least on Search volume. The image below shows the Google Trends for these technologies
silverlight [blue]
adobe flash [red]
adobe flex [orange]
adobe air [green]
        A.    Adobe AIR Puts Companies on Desktops
        B.     Adobe Introduces Adobe AIR, Adobe Flex 3 Software
        C.    Nokia to bring Microsoft Silverlight to mobiles
        D.     Microsoft reveals new content partners, DRM for Silverlight
        E.    Microsoft to highlight Silverlight, ‘Oslo’ at show
        F.     Onstream Media Debuts Microsoft Silverlight Webcasting Service
So the long and short of this is that Silverlight is likely not causing Adobe to lose sleep at night, but rather giving them one of those a rough, restless nights … knowing that soon Microsoft will launch a credible product aimed squarely at them.