8 or 9GB DVD+R/RW?

Please forgive a newcomer if this is an ignorant question, but I just obtained a new Plextor PX-708A and am enjoying backing up my DVDs with it, even though some compression is usually required to maintain the integrity/structure of the original. I wanted to know if there are 8-9gb single sided DVD+R/RWs in the future, and will standard writers like the plex be able to write to them? Thanks!