It looks like Hall won't be the only player in the training room to start camp. Most notably Gwynn and Bourgeois seem to have some early issues that could impact their chances of making the team if they don't heal up quickly.
EDIT: A quick rundown:
Hall's injury is as previously thought, partially torn calf, 4-6 weeks.
Gwynn has a shoulder impingement and will not be allowed to throw.
Jason Bourgeois has a broken left pinkie finger.
Alex Periard has tightness in his shoulder.
Chris Capuano and Mark Rogers still cannot throw as they recover from their respective arm troubles.