According to Blu-ray.com, Sony and Panasonic have developed a new technology that will allow the layer capacity of Blu-ray to be upped from 25GB to 33.4GB. Apparently, exisiting devices would just need a simple upgrade to read all 33.4GB.
<blockquote>Sony and Panasonic have announced that they have developed a new optical disc evaluation technology that will allow the layer capacity of Blu-ray media to increase from 25GB to 33.4GB using existing Blu-ray laser diodes. This would presumably allow existing Blu-ray hardware - including Blu-ray Disc players and burners - to play the proposed discs with a simple firmware upgrade.
Currently, disc evaluation is accomplished by analyzing disc jitter, but at higher capacity, that technique becomes unreliable. Sony and Panasonic resolved this by developing i-MLSE (Maximum Likelihood Sequence Estimation) evaluation index, which can perform the same function as jitter but at higher capacities. </blockquote>
News Source: <A href="http://www.blu-ray.com/news/?id=3977" target="_blank">Blu-ray</a>