Communication from the Commission to the European Parliament, the Council, the European Economic and Social Committee and the Committee of the Regions – The impact of free movement of workers in the context of EU enlargement – Report on the first phase (1 January 2007 – 31 December 2008) of the transitional arrangements set out in the 2005 accession treaty and as requested according to the transitional arrangement set out in the 2003 accession treaty