According to Linux Journal's Product Insider Adobe has just released yesterday an alpha of their AIR platform for Linux. They've got a free download directly from Adobe's site in English and later this year when they finally launch the product it will also be available in other languages as well.
I do believe this is a very interesting move from Adobe, seeing as how Silverlight seems to really be picking up steam and is less likely that development tools for it will be released from Microsoft directly, though apparently some tools will available from Novell (at last through the use of Mono). At any rate, it is good news to have an integrated development platform for Rich Internet Applications from Adobe.
Where exactly do you see Silverlight being picked up?
Silverlight and Flash aside, I don't think we ned even MORE proprietary crap on GNU/Linux - not from Adobe, and not from anyone else. It will take some time until free replacements are there to fulfil everyone's need for any given application, but proprietary software compromises the platform and does not foster development in that regard at all.
To my knowledge there is no Open replacement for technologies such as Flash or Silverlight. Open implementations, yes, but no actual replacement alternative (like Vorbis to MP3). SVG could be the vector backend, but there's no actual scripting and rendering mechanisms in place. I'd like to see such a replacement.