Market socialism examples are Yugoslavia and Poland in the 70's. Nordics have capitalism with (currently being cut) social safety nets, one of prime characteristics of socialdemocracy, ideology that do not promote socialism but capitalism with "human face", as Nomad said, based on Keynes work. Blair and his followers in many countries went much off even that into the neoliberalism.

That's not market socialism, at best it's called Keynesianism.