Earlier this year, Mempile unveiled the TeraDisc, which would be able to hold up to a theoretical maximum of 5TB using 200 layers and blue laser technology.  Up until now, one major issue with adding more layers to media is that the amount of light reflected becomes low and noisy to the point where reading back the data is near impossible.  So Mempile's main goal has been to overcome this limitation.  After trial & error of various materials, they have developed a special polymer that is almost entirely transparent to the drive's laser light.  The media colour is yellow as a result and not publicity stunt as it may appear to be.

The red laser TeraDisc in development consists of about 200 virtual layers created by the laser and each layer contains a capacity of about 5GB of data.  While the current prototypes hold around 600GB to 800GB, the company's target is 1TB with a 1.2mm disc thickness in the very near future.  Unlike traditional optical media that uses pits and lands, this media uses ePMMA molecules and nonlinear optics for recording.  Mempile's use of nonlinear optics allows data to be recorded and read by focusing the laser beam to a small radius, but prevents recording & reading with just a slight increase in the beam's radius thus allowing it to penetrate the upper layers, unlike linear optics where some light is absorbed as it penetrates through each layer. 

The current prototype uses red laser, but when a blue laser is version is developed later on, this will allow for a theoretical maximum of 5TB per disc.  The archival life for the TeraDisc is predicted to be around 50 years.  Going by this TFOT interview with Mempile, they expect to have a prototype in 18 months followed by drives and discs intended for the consumer market available about a year later.  The first drive is predicted to be $3,000 and around $30 to $50 per 600GB disc.  However, they expect pricing to rapidly drop as the manufacture of these drives and discs increases.
 
Thanks to Andrei and DamnedIfIknow for letting us know about this news.  In depth information, including some optical disc history and a Mempile interview can be read here on TFOT. 

Andrei added the following comment:  Some old Balkan words of wisdom say that when two fight the third may win. An adapted translation would say while BD is fighting HD-DVD the Terra Disk may win. An Israeli company is just about to create more CD freaks .

"Using ePMMA, Mempile was able to create a media with about 200 virtual (i.e., created by the laser) layers, five microns apart, each containing approximately 5 GB of data. Although current prototypes are still in the 600–800GB per media range, Mempile is convinced that further optimization will enable it to reach its goal of 1 TB per 1.2mm disc in the very near future. "

Hopefully this cool transparent media would not remain a prototype since 1 TB cd would cost around 30 bucks