Jim Wyatt just announced that Rusty Smith has officially joined the Titans practice squad. This is best case scenario for the Titans. Rusty doesn't count against the 53, but he is still with the team. It keeps them from being in a situation where they have to add a quarterback on short notice that doesn't know the offense.
They can bring him up to the active roster if Jake Locker sustains an injury that is going to keep him out of for a week or longer.
Wyatt also reports that Damian Williams will be the Titans emergency third quarterback on game day. This is nothing new as DWill filled that role 11 games last year when Rusty was inactive. Let's hope it doesn't come to a situation where they have to use him.