The requirement for nationals of the A8 accession states to join the Worker Registration Scheme ceases on 30th April 2011. This fact was established in a parliamentary written answer on 5 July 2010.
http://services.parliament.uk/hansard/Lords/ByDate/20100705/writtenanswers/part051.html
More information and background on the scheme can be found by clicking on the link below.
http://tinyurl.com/6djup7g
If they have not already done so, Employment Businesses need to revisit their processes and paperwork to cancel reference to the Worker Registration Scheme.