Zion Movement is a Chicago-based Gospel choir formed of singers and church music directors and led by Dexter Walker. I had the privilege of being led in worship by them this past weekend at Willow Creek. They closed the musical worship portion of the service with what seems to be their most popular song, "I'm Saved." Afterwards, I purchased their recent album "Hope," and was able to talk to the leaders.
More information (e.g. background, downloadable music, bookings, etc.) can be found on their Facebook page, last.fm, and iTunes. A link to their most recent album is below: