I was so excited to hear about this!
The Highlander: The Source Official Site gives a glimpse of the upcoming movie:
The world is falling into chaos. As he roams a crumbling city, Duncan MacLeod (Adrian Paul), the Highlander, remembers happier times before the love of his life left… Hopeless and alone, MacLeod finds his way to a band of immortal companions, including his mysterious friend Methos, and a mortal, Watcher Joe Dawson. Together this small group sets out on a quest to find the origin of the first Immortal and The Source of their immortality.
This will be the first in a Highlander trilogy.
The first trailer can be seen below: