I has sent my eldest to nursery when he was 3, while my second one did not go.  I didin;t notice any dfference in terms of their earning capabilities or adjusting in school.  Have also come across some media reports that show negative influence of nurseries/daycares.

http://www.guardian.co.uk/society/2007/apr/05/childrensservices.earlyyearseducation

On teh otehr hand some people speak very highly of few nurseries.