Check out this article from the Star-Telegram summarizing the Build Day! Here's a snippet:
As clumps of snow fell off trees in Arlington, [Dikembe] Mutombo and other players helped parents, teachers and other residents haul mulch, mix concrete and set colorful jungle gyms and swing sets in the ground. Volunteers started the work at about 7 a.m. Players came in the afternoon to help, and it was all to be finished by about 4 p.m.
"I love what the NBA has done with this day of caring," said San Antonio Spurs forward Tim Duncan, who worked through the afternoon. "Getting guys out and giving back to the communities we're having our games in, it's a really great thing."
Read the full article here: All-Stars lend a hand to build playground (Star-Telegram)
You can also watch this great video of the players at the build from NBA.com!