Rasheed Wallace is indeed retiring, according to Gary Washburn of The Boston Globe:

After weeks of speculation about his status for next year, Rasheed Wallace indeed plans to retire, according to his agent, Bill Strickland.

Following the Celtics' Game 7 loss in the NBA Finals, reports indicated Wallace was leaning towards retirement. Yet, as the summer progressed, Wallace hanging them up didn't appear to be set in stone, as a few players publicly acknowledged the possibility of him returning, including Paul Pierce. That notion was spurred on recently when the newly acquired Shaquille O'Neal made a public plea for Wallace to return.