I wish it did. I mean, it is just CO2, which does help plant growth, so it should and could help. But as near as I can figure from reading about it- the CO2 from brewing, and from the various other small scale CO2 emmiters that are out there for purchase, isn't really produced in large enough quantities to make much difference. I think it could be very helpful if you have a micro grow and set things up just right. Anything larger than that and it's difficult to find a way to contain the CO2 and keep it in contact with the plants. It likes to come out of the bottle and go on its merry way, never to be seen again (Well I guess it wasn't ever seen to begin with, since it's invisible... ).
As soon as a vent fan comes on - goodbye CO2.
This is just my take on things without having tried it. Would be happy to hear different though.