In a return to the problems that have affected laser disc, CD and DVD at various times, it appears that some Blu-ray discs are suffering from some kind of disc rot. Member of AVSForum have reported the problems, and have even uploaded pictures to show what it looks like. The small marks, which look like small mould blooms are below the outer surface of the disc, so cannot be cleaned off. They also stop the discs form playing.
The main reported issue seems to be with The Prestige, so it might simply be the case of a bad batch, but if it is, then the disc factories will need to tighten up their procedures. A recall and replace for a multi-million selling BD in the future won't be a cheap exercise. Other reported titles that have been seen with the rot are The Departed, Stranger Than Fiction and Gone In Sixty Seconds.
For everyone with a bad disc, however, there are two or more who have OK discs, which doesn't help narrow down any issues. Local ambient humidity doesn't seem to play a part, as people suffering from the problems are all over the place.
Disney (behind The Prestige) are taking this seriously, and are replacing discs for people, as are Amazon.com if that's where you bought your disc.
Expect more of this over the coming weeks as people become aware and start checking their discs.