The Blu-ray Disc Assosiacion has not yet started the standardization procedures for this kind of media, and according to TDK, the four-layer BD-R disc is currently a research level prototype. TDK held a BD-R recording test, using a Pioneer BD-R/RE prototype recorder. The TDK disc was recorded at 2x, which translates to 72Mbps transfer rate.
Single layer (25GB) and dual layer (50GB) BD-R and BD media were also available at the TDK booth, featuring the DURABIS 2 coating technology.
Additional information for the Data Storage Expo is available at http://www.watch.impress.co.jp/av/docs/20050630/dsexpo.htm.