This was pretty widely expected. Coleman's official pre-recount lead was about 200 votes out of some 3 million. That's like 200 pennies out of $30,000.00 - literally a rounding error. The thing is, Minnesota uses optical scan ballots that, like most machines, are good but not perfect. They pick up clear signals (i.e. darkly filled in bubbles), but the law allows in a close race for the counting of ballots where a choice was marked in a way that is obvious to a human being but not to a machine. Guess who's likely to make a lot of those sort of errors? Inexperienced new voters. Guess which party new voters generally supported?
This race is far from over, but if you wondered why the vote total appeared to be moving towards Franken, that's why; his votes were disproportionately undercounted the first time around. We'll see what happens.