With 2536/2541 precincts reporting, Democratic candidate Mark Herring trails Republican Mark Obenshain by only 153 votes.
This follows the slow narrowing of the margin over the night, along with adjustments as AP found errors in its count. The person who I have noticed most up to date on this is @redistrict, Dave Wasserman, who is the US House editor of Cook Political Report. His Twitter:
It has been an interesting race to follow tonight, but the outcome will probably be determined tomorrow and/or with a recount. Have a good night
Tue Nov 05, 2013 at 11:11 PM PT: Update 2:10am EST: AS a number of people have already noted in the comments, the updated toals show that with 2537/2541 precincts reporting, Mark Herring now leads by 616 votes!