As show in http://youtu.be/M-gdbqMihAE by Docm77 there is a new found exploit in breaking through the bedrock layer. It is also is being discussed on reddit here http://www.reddit.com/r/Minecraft/comments/1qdmqm/how_to_break_bedrock_in_vanilla_survival_172/ .
Related issues
duplicates
Comments
CubeTheThird
migrated
Nathan Adams
Can confirm.