Unfortunately, probably not. Celtics fans can dream all they want about the possibility of seeing Howard in green, but those dreams died when Howard waived his ETO and decided to stay with the Magic for one more year (at least until next trade deadline).
Sure, the Celtics could make a play at acquiring Howard, but the Magic aren't exactly going to be giving him away. Why? He's still Dwight Howard, the best center in the NBA (sorry Andrew Bynum). For the Celtics to land Howard via trade, they will have to give up some big time players and picks, and they don't have any big time players anymore.
Rajon Rondo would definitely have to be part of that deal. That's something I wouldn't prefer, but with the way Avery Bradley has been playing as of late, I would be a little more comfortable with that (although Rondo is the superior point guard, and it isn't even close).
Let's not get ahead of ourselves. Orlando is going to be seeking some young talent to lead them into the future, and Boston just doesn't really have that. Sorry to spoil the fun again.