The default (included) theme should allow use of Google Web Fonts to set the font face of the title font (and perhaps other page titles). http://www.google.com/webfonts
Just like the twentyeleven theme allows for configuration of header and background images, it should allow for configuration of header fonts. Perhaps the configuration page provides a handful of font options, with the ability to manually add additional fonts.
Since the Google Web Font API supports optimization through specification of limited alphabet set, WordPress should provide methods to obtain the limited alphabet set based on the blog title.
By supporting Web Fonts in the default WordPress theme, we encourage other theme developers to make use of web fonts. WordPress sites will look more pretty.