No, any indie who wants to can apply to be a ps3/ps4/vita developer. There are some minimal requirements but I haven't heard of folks getting turned away.

On top of that Sony has also been actively courting indie developers with interesting games and doing things handing out 'loaner' devkits to make the development process less expensive.

I know several 1-5 man teams that are working on Sony titles and they are all very happy with their relationship with Sony.

It sounds like if Sony invites you then at least you get to keep the money from your game. If MS invites you then a middleman publisher takes a slice of your revenue.

If you don't have an external publisher then Microsoft or Sony must agree to be the publisher on XBLA or PSN. I think on both consoles every title gets assigned a product manager, for example.