Question: I am amused by the story of Beethoven dueling another composer in Vienna, in which he takes the other composer's music, puts it upside down, and proceeds to humiliate him. I feel as though keyboardists with that kind of talent must exist nowadays, but they are perhaps not as popular as they once were.

Do we have such "Rockstar" pianists in the modern age? Who are they?

Answer: 
The type of keyboard music typically composed during the classical age was so much less complex, and the number of professional musicians was so much smaller, that the comparison cannot be made in any reasonable way. 

A lot of present-day pianists could probably sight-read the music of a second-rate composer from 1800. But that was a time when the music of Liszt, Alkan, Ligeti, Messiaen etc. etc. did not exist, and would have been considered absurd and obviously unplayable. It is impossible to say whether there are living musicians who are as phenomenal by current standards as Beethoven was by *his era's* standards.
[Jordan Rudess](http://www.jordanrudess.com/) (Dream Theater) is an impressive keyboarder and a true wizard, maybe not quite as famous as Beethoven. He's not only an accomplished piano virtuoso, he's also constantly pushing the boundaries of his instrument, e.g. by controlling and designing sounds in innovative ways such as with the Haken Continuum and his iPad apps.