Font anti-aliasing technique in Chrome changes after 48px size
Google Chrome does render fonts with subpixel anti-aliasing but the text looks more jaggy than in other browsers, because it only supports horizontal anti-aliasing.
The jaggies are specially visible on the top and bottom of the curved letters, like S, O and C, while looking fine on the sides of these letters.
Look at the screenshots of some letters with the Georgia font at 48px:

Google Chrome 18.0.1025.100 beta-m - Georgia at 48px
Can you notice the jaggies on the top of the letters in Chrome?
But after a certain font size, Chrome does some other method to render fonts. In Georgia font, that size is 49px:

Google Chrome 18.0.1025.100 beta-m - Georgia at 49px
The letters are no longer jagged!
If we take a closer look, we can see that while it does look better, it’s not using sub-pixel rendering, but monochromatic anti-aliasing for both the vertical and horizontal directions.
Here’s a closer look at the fonts rendered above, amplified at 500%:

Chrome - Georgia 48px @ 500% zoom

Chrome - Georgia 49px @ 500% zoom
Conclusion: for now if you’re using a big font-size for headers or page titles, consider font-size: 49px
to get the smooth edges on Chrome, at least until they use subpixel for horizontal + monochrome for vertical anti-aliasing like the other browsers.
More information about font rendering:
http://en.wikipedia.org/wiki/Subpixel_rendering
http://blog.typekit.com/2011/07/26/new-from-typekit-improved-font-rendering-on-windows/
http://www.basschouten.com/blog1.php/font-rendering-gdi-versus-directwrite
For browser comparison, here’s how the same text is rendered in Chrome 18 beta, Firefox 11.0 and Internet Explorer 9:

Chrome 18.0.1025.100 beta-m - Georgia at 48px

Chrome 18.0.1025.100 beta-m - Georgia at 49px

Firefox 11.0 - Georgia at 48px

Internet Explorer 9 - Georgia at 48px
ant the close-ups:

Chrome - Georgia 48px @ 500% zoom

Chrome - Georgia 49px @ 500% zoom

Firefox 11.0- Georgia 48px @ 500% zoom

Internet Explorer 9 - Georgia 48px @ 500% zoom