The line adds new stations in Fairfax County in Virginia (including connections to Tysons Corner), runs through DC (matching the existing Orange Line) and then travels to Largo in Prince George’s County. This phase of the expansion is anticipated to be opening in a few months. Ultimately (maybe in 2018) it will connect to Dulles Airport.
The article has a picture of a large, covered, and secure bike parking facility that was built for the station. Planners for the project are working to integrate multimodal alternatives and anticipate that the line will serve suburb-to-suburb commuters, increase train frequency in downtown, and improve some train congestion problems. Silverlinemetro.com – by WMATA – has many more details.