Empathy's "Ubuntu" Theme Is quite attractive.
Is there any way of using empathy themes on pidgin(specifically the Ubuntu Theme)?
The short answer, no.
Empathy chat themes are made to support Adium based themes (Mac only IM client). A FAQ link about Empathy client (the first 3 questions answer questions about Empathy themes and how to create your own):
Pidgin themes uses a XML file to create buddy list themes which can also control the style of the messenger as well:
Since the Adium Message Style code ( http://trac.adium.im/wiki/CreatingMessageStyles ) uses a different structure then Pidgin, the conversion process might take awhile but can be done.
If you really like the Ubuntu message style for Pidgin, converting it to that buddy list theme XML file format might be the best way. Once its converted, it can be offer to the Ubuntu packaging team so they can use it for future installs (just putting that out there ... wishful thinking).
The location of the Adium message style that you like can be found here on your system:
I hope this explains more about Pidgin and Empathy themes.