I realize ending a english language sentence with a preposition has found itself into the vernacular. It is still wrong. "About (Of) what are you writing" may sound aristocratic or archaic, but it is a better translation and the word order fits well with the Russian in this example. I would prefer using, "Tell me about what you are writing." Yes, I am an old f*rt.
Agreed - and since both the "current vernacular" (must be a bunch of young folks) and the correct English grammar translation get the same meaning across to the reader both should be accepted as correct - or if we are also trying to teach correct English grammar structure in these lessons only the "archaic" - correct translation should be acceptable.
I know a link was already posted, but i like this one. http://www.russianlessons.net/grammar/pronouns.php