Top comment !!!
I completely agree. Starting a sentence with "so" implies some continuity of a dialogue that the listener hasn't been aware of..kind of "ah, you haven't heard about this, I'll just bring you up to date". At best it's ridiculous grammar and at worst it's an attempt to dismiss the legitimacy of the questioner's challenge and is patronising as f*ck.
It annoys the f*ck out of me as well and the Winklevoss's are the worst culprits.
On a related note, listen to them try to explain Bitcoin - instead of just saying "its peer to peer money that doesn't need a bank as a counterparty", they go on about cryptology and C++ programming !?!
http://www.businessinsider.com/winklevoss-twins-explain-what-bitcoin-is-2013-11
So it's okay to pointlessly swear in most sentences?