Jeff Jarvis did an excellent post on The new metrics of campaigns which compares several news, search and microblogging measurements per democratic campaign and comes up with Barack Obama, overall, leading. Some of the metrics measurements he's pulling from are services I've not used before, like Daylife.com (does an article count for any subject).
The only thing I'd say about the Internet metrics of campaigns is that they'll be increasingly more important as time goes on. However, in this election, they'll probably only reflect the voting preferences of that part of the voting population that actively uses the Internet - and while the majority probably do use the internet, to some extent - it's not enough to account for the differences that can push an election one way or the other.
By 2012, I'd say the internet will rule elections - but for 2008, internet campaign metrics should be used more like as a pointer - not a conclusive poll.
