A system of cooperatives is not "socialist" unless it changes the relations of production away from what currently exist under capitalism. This means ending production for market exchange, pricing systems, wages etc. in addition to common ownership of the means of production. The end result being a system where workers freely associate and produce to satisfy the needs and desires of themselves and their communities, not to facilitate the expansion of capital.
IMO cooperatives are a progressive step forward within capitalism, and should be promoted to introduce ideas of economic democracy and alternatives to capitalist value production into the public consciousness. However, without some way of planning and networking co-ops together they can only reproduce capitalist social relations, albeit in a "nicer" fashion.
