Update: This change made it into an earlier release than originally expected. It's effective for the new 22.214.171.124 release.
In another bit of housecleaning and streamlining the plugin, we've decided to remove the TwentyTen theme-specific rules from the default forms.css file starting with the release of the 126.96.36.199 version. That's one less thing for us to maintain and it also reduces code bloat for everyone that's not using the current WordPress default theme.
To be clear, this doesn't mean we're dropping support for the TwentyTen theme itself, it simply means we're not including those theme-specific styles in the default stylesheet from now on. If you're using the default TwentyTen theme for your site, you can still grab the styles from the link below and add them to your theme's style.css file.