So I'm not sure if /vp/ knows this yet, but after investigation with the new Pokemon file format and how shininess is determined, some new stuff was recently discovered.

Basically, the base shiny rate is now doubled, or 1/4096. This is the rate that applies to random encounters and hatching normal eggs. This means that Masuda Method now has a roughly 1/683 chance of yielding a shiny.

The rates for fish chaining and Friend Safari are still unknown, but this basically means that if you've thought shinies were more common in general, they are.