Is it a coincidence that the Nintendo Direct stream is on the same day as the Vita launching? They will probably announce something to take attention away from the Vita like they did at TGS, so it may be an important 3rd party title that is still under wraps.
Yes, it's coincidence. If they wanted to take away attention from the Vita launch, they should have held this event a week ago. By the time the news of this event make their way around, many people will have already bought the Vita.