I'm on a macbook pro running OSX v. 10.6.2 and installed Google Chrome v. 5.0.307.11 beta. My font manager is FontAgent Pro 4. Everything was working great for a week or so and all of a sudden all fonts on any page I visited were replaced with the A's in boxes. As many people have pointed out, the issue is related to Font Managers managing your system fonts and having duplicate fonts in your system font folder.

The solution that worked for me:
Quit all applications
Opened FAP4 and assigned it to manage my system fonts. (under preferences)
Disabled all Arial fonts
Restarted
Opened Chrome
Fixed!

Hope this helps!!