Yeah, but I don't know of any dual-layered, dual-sided Blu-Ray discs, so 50GB is currently the limit. I've never much seen the point in dual-sided discs other than space-saving - if you're gonna split it up anyway, why not just use two discs? There's much less chance of damaging the disc, and dual-layered, dual-sided DVDs are notorious for fucking up all the time.
I'm more interested in these 16-layer 400GB discs that Pioneer is developing ...