SVG 1.1 became a W3C recommendation on January 13, 2003. Six years later, this page records results of running various SVG implementations (web browsers and browser plugins) through the official SVG Test Suite.
Last updated 2009-03-29.
more detailed table @ http://www.codedread.com/svg-support-table.html
The following picture indicates the results of running all 280 tests in many SVG implementations in the wild. Each test takes up a two-pixel strip in each column. I use a top secret scoring system … ok, well actually I just use GREEN for "Pass" (2 points), YELLOW for "Almost Pass" (1 point), and RED for "Fail" (0 points). The "Almost Pass" scoring is subjective, so think of it as me giving out points for trying.
Now I know that I'm going to get complaints that the SVG test suite doesn't cover all functionality (I agree with you), nor does the score give a fair indication of other factors like performance (again, I agree with you), so please take this page as what it is: A data point from a guy who had too much time on his hands but is interested in seeing how the overall quality of SVG implementations improves in the future.
I wonder why IE 7 and IE 8 have no native support for svg, 6 years later :sherlock: