That simply is not true. While Virginia may be trending blue, it will not meet that threshold by 2008. Also don't forget; elections are about candidates and issue stances; especially in Virginia.
Lets revisit 1992 as the Old Dominion had just elected a democrat Chuck Robb to the Senate in 1988 and Doug Wilder to the governor's mansion in 1989. Virginia must have been "turning blue" then too huh? The dems even had serious control of the General Assembly as well. As it turns out, Virginia again delivered its electoral votes to George H.W. Bush; even with the large Perot vote holding his margins down.
I see the same thing developing right now here in Virginia. The Virginia electorate is very smart and typically votes for the person. That being said, it is still intristically conservative. The problem posed in Virginia is that when a democratic presidential candidate wants to win the state; they have to devote vast resources here (and unlike any other campaigns, presidential ones have limited money) to get us to even. In 2004 everyone thought Virginia might be in play, but it ended up being the usual GOP win b/c the dems can't afford to gamble here when money starts to get tight. They have a much better chance in states like Ohio, Wisconsin and Florida.
Even with the seemingly democratic turn in Northern Virginia (which I am not totally sold on), the downstate areas can still offset when the turnout is jacked up to 65-70%. I think if a dem in 2008 takes aim at Virginia; they will find themselves making a big mistake.
I agree that Virginia could become the next Ohio in the next few years, but we aren't there yet.