Absolutely.
He actually did a pretty good job at the PG spot for us last year, and was perfectly capable as a backup behind Rondo. Not only did he handle the ball very well (he had an assist/turnover ratio of around 3:1) he also gave us another offensive threat on the floor at that PG spot.
Right now aside from Rondo our backup PG options are Pressey (who has never played NBA minutes), Bougans, Crawford, Brooks and Lee. Neither of those guys is even close to an efficient ball handler except Pressey, and we have no clue how he'll pan out yet.
I wouldn't at all mind having Barbosa either as a backup PG or a third string PG. At the very least it would give us a second capable PG (along with Pressey) in the even that Rondo can't play right away.
Once Barbosa went down our lack of a decent ball handler became very evident and it hurt us badly.