What is going on with dvd release dates?

I’ve noticed that more than a few dvds are having more than 1 dvd release. I understand that it are different dates for different regions, but lately it’s just weird. Posters have one date one them and then there’s another release date and then another one. Or that it’s out in dvd and you can watch it on tv, but you can’t rent it anywhere. Not even on Netflix. Does it have to do with Hollywood Video going bust? What’s going on?