Some places are doing double-sided (9.4Gb) discs, but there are no single-sided discs larger than 4.7Gb. This is the dvd standard (dvd-5), the only other would be a dvd-9 (single-sided, double-layer) and there are, and is never likely to be, any double-layer recordables. Whether or not a larger size of dvd-5 is ever released (ala 80/90/100 min cdr's) remains to be seen.
Wrong forum btw. Post queries like this to the "DVD Players and Recorders" forum in the Hardware section in future.