This year the press conference will take place on September 1 at 2AM (ET; August 31 at 11PM PT). Last year, the conference talked about PlayStation/Vita TV, Guilty Gear, Yakuza, and a handful of other games. Hopefully this year's show is a bit more impressive.
Tokyo Game Show 2014 itself actually doesn't even kick off until September 18. It will run through to the 21st.