I have been waiting for Firefox to support SVG for ages now.
It's one of the largest missing pieces to turn Firefox with XUL into full fledged portable applications platform. There are other gaps too, such as 3D support and media support (without plugins that may or may not be available on all platforms). However with SVG at least the 2D graphics area is reasonably well covered.
And I'm looking forward to fun stuff like monitoring app's using AJAX (i.e. XMLHttpRequest) to request data updates and adding elements to an SVG drawing instead of reloading an image, map applications using SVG for their information overlays (or even the full map, though I'm unsure how that would work out performance wise), AJAX style business graphing applications (reporting interfaces with fancy graphics will suddenly become a hell of a lot easier to do in a browser)