From the Boston Herald:
The hopes of Dennis Seidenberg returning to the Bruins some time this season remain slim, but he took a significant step yesterday. According to a source, the defenseman skated at Ristuccia Arena for the first time since undergoing knee surgery.
It’s believed he skated for about 15 minutes, and it’s not known just how well his knee held up, but it is a noteworthy milestone in his rehabilitation.
A few weeks ago, the Bruins refused to rule out the possibility of Seidenberg returning in the playoffs, though the team would likely need to make a deep run for that to happen.
If the playoffs started today, Boston would face Columbus in the first round. (Detroit and Philadelphia are also potential opening-round match-ups, with Washington and New Jersey mathematically possible, though unlikely.)
If the Bruins advance to the second round, they’d play the winner of the all-but-assured Montreal-Tampa Bay series.
-- Jason Brough, NBC's Pro Hockey Talk