Customizing Color Fonts on the Web
webkit.org
webkit.org
Any other Mac users see that, or is it just me?
Though I agree it could use a few more inline with the live examples, so you can check if your browser is already using what they announce.
Still though, I see the same as you describe in Safari.
They do however render coloured fonts in non-Safari browsers (using basic CSS features that have existed a long time), but they're monotone per-character. The new safari feature supports multiple colours shown within a single character at once.
The lack of screenshots makes the article very confusing for non-Safari readers (as I mentioned in another comment)