Today i woke up to news that there is a "leaked" Batman vs Superman trailer on the internet. I have been searching for it to no avail. No one seems to have uploaded it on youtube yet, officially or otherwise. So here is the latest update from those who claim to have seen it on 4chan.
The trailer starts with footage from Man of Steel showing the destruction of metropolis while Bruce Wayne/Batman (Ben Affleck) narrates. Batman seems to be question Kal-L/Superman's intentions towards Earth and its people. Batman then says "Is Superman here to save us...or destroy us. I am goint to find out".
If you ask me from these descriptions it sounds like a trailer did leak and WB have somehow stopped it from going viral which is good. All in all i expect an official release of the teaser around March 2015. Since principal photography for Batman vs Superman:Dawn of Justice is finished, its best for us to be patient since the movie will be released in 2016 anyway.