Since Vine is not available yet on Windows Phone, there is an app called 6Sec which right now is in private beta with daily updates. Like the Instagram knockoffs, which don't use the app's APIs, 6Sec uses a relay server to get your video to Vine's servers. So far, 900 beta users have uploaded 600 videos while the developer promises a Live Tile for the app and a better UI.
Eventually, Vine will most likely offer a Windows Phone version which will make 6Sec extinct, like a dinosaur.
source: 6Sec via WPCentral