At 97.5 percent, it's Allen by less than 5,000. But the remaining precincts are heavily black areas of Richmond, and parts of Fairfax, which is heavily Democratic. MSBNC reports that Webb staffers also say most of the 30,000+ absentee ballots are from Loudon, Fairfax, and Prince William Counties. Fairfax will deliver pretty significantly to Webb. They think Loudon and Prince William absentees will favor Webb, too, but by slighter margins.
A recount is certain, now. The only question is who will begin the recount with a lead. Webb and Allen staffers may want to think twice about which position they'd rather have. Some strategists actually say it's better to be behind in a close recount, because you can keep counting and searching for votes until you find enough to take the lead. In most states, the first recount is easy. Winning a second recount after you've been overtaken by the first one is generally quite a bit tougher.
Not exactly sure what the procedure is in Virginia after the first recount.
UPDATE: CNN and the Richmond Times Dispatch are reporting that Webb has pulled into the lead, by about 2,300 votes. The Virginia Secretary of State's Office still has Allen on top by less than 2,000. The CNN numbers show a larger total number of votes cast, so maybe they're getting info that's not making it to the website.
UPDATE II: With about 18 precincts left to report, the Secretary of State's Office now shows a less than 2,000 vote lead for Webb. Provisional and absentee ballots will be counted over the next week.