Sharp has announced that by April they will begin production of new laser diodes powerful media that can burn Blu-ray in 6x. They will be available in a 5.6mm diameter for 5.25" engravers but also a 3.3mm for the manufacture of burners for laptops. Their price is still very high, over 300 Euros (~$450 USD), however, to be a significant obstacle to the democratization of engravers.
Note that Sharp already had in the pipeline diodes whose power could, in the future, allow burning dual-layer BD-R up to 12x, the theoretical maximum limit for this format. They will not be available until 2009.
[translation by CliveAtFive]