Nico Nico Douga has previously been announced as one of the Playstation Vita’s first third party apps and will be readily downloadable on the Vita Playstation Store starting from the 17th December as a free download. For those who are unaware what the service is, Nico Nico Douga is something along the lines of Youtube where you can post and browse videos, but with the added bonus of being able to make comments on the top of the videos, sort of a live commenting system. While you only get the basic features upon release, in 2012 they intend on allowing you to post videos, host live broadcasts and if the game permits, do broadcasts of your gaming sessions live (A feature the Playstation 3 could also use). The official website for this app can be seen HERE.
As we now have an English Nico Nico service, it might be possible to see a release with the English Playstation Vita console, however nothing official has been announced yet.