The latest advance by Facebook (and Instagram) on Twitter territory in their increasingly heated partner war a video sharing service that looks a lot like Vine, Twitter's increasingly popular looping video app. Stay tuned for all the details and a complete first look, but remember, too, that Facebook is little late to the social video trend — remember they were supposed to be the biggest new thing a whole year ago? — and know that Facebook is releasing this product through its $1-billion baby almost completely because of the success Vine has enjoyed in the App Store since its launch this spring. Facebook announced today's announcement by saying that a small team was building something big, when in reality that was probably a mad dash to catch up to a big competitor that made a small app turn into a huge challenge to its mega-acquisition last year. Indeed, Instagram and Twitter have had a little war for mobile users going since Twitter added filters to its pictures and Instagram pulled its pictures from Twitter. To wit, just before the announcement Twitter teased a Vine update of its own, showing what looks like a redesigned Vine interface that blows the video up to the full width of a phone screen.