After sometime, I have found out that actually Yahoo User Interface (YUI) Library does talk to WordPress.com but it is commonly not utilized by its users.
I have not yet got anything useful for my websites, but it has become my passion, exploring more possibilities of YUI talking to WP.com.
I have been developing various WordPress themes and plugins in order that bloggers can use my themes in their blogs.
The driving aspect of my work is the elegant display of the YUI CSS Styles: both YUI CSS Grids, YUI Container, YUI Tabview and YUI Accordion. Besides, YUI Javascripts library also very good to use, as everything is well-structured. I just need to know how to call each file/ library from WordPress plugins or themes.
Finally, I have come up with at least 6 varieties of WP Themes, two WP Plugins.