It's looking more and more likely. Weigel passes along the above chart from electoral-vote.com:
[O]nly in the last week have the numbers on U.S. Senate races suggested that the Democrats — who have more seats in play, and more open seats to defend — are winning. Dark colors indicate that one party is winning; a light color line indicates that there's a lead, but it's close. Today's map has Democrats holding at least 52 seats when the election's over.
Silver's analysis:
[T]he odds of a favorable overall outcome for Democrats have increased in recent weeks. The forecast model now gives them a 70 percent chance of controlling the chamber, either by having at least 50 seats and the presidency, or 51 without it.
The Dish 