Adobe has announced that they will discontinue further development on the Adobe SVG Viewer. In case you weren't aware, the Adobe SVG Viewer has been the most popular web browser plugin used to view SVG graphics. Illustrator has been able to open, export, and roundtrip SVG files since version 10.
Apparently, much of this decision has been based on several facts. First, there are many browsers (such as Firefox) which natively support SVG without the need of a plugin or viewer (although it isn't currently as robust as what the Adobe SVG Viewer supports). In addition, Adobe of course now owns Flash, and is looking to that technology as a platform for developing such content. In fact, I think it's interesting that in the FAQ that Adobe has put out, they mention that "as an alternative to SVG, you can consider developing your application using Flex".
I think it's important to point out that it doesn't appear that Adobe is abandoning support for SVG in their authoring applications. For example, Illustrator CS2 currently supports SVG Primitve objects, SVG Filter Effects, the opening of SVG files, and the ability to export SVG 1.1, SVG Basic (PDAs), and SVG Tiny (Cell Phones). It just appears that Adobe is leaving the job of viewing SVG files up to someone else. Remember that SVG is an open standard, and in no way does Adobe own the SVG format.
So if you're using SVG today, you can still count on using Illustrator to author your content. You just might need to rely on something else in order for you or your clients to view that content.