As the European Union gives Romania and Bulgaria the go-ahead to join the club, there is speculation the UK will see the arrival of more workers from these two countries from 2007.
In May 2004, eight other Eastern European nations joined the EU - and the UK was one of the few countries to give their citizens free access to our labour market. So what do we know about what has happened during the past two years?
The figures are incomplete, not least because the situation changes by the day, but there is enough information already available to show that the arrival of workers from Eastern European states has had a profound effect on the UK.
WHO ARE THE WORKERS?
The eight nations given unfettered access to the UK's jobs market in May 2004 were the Czech Republic, Estonia, Hungary, Latvia, Lithuania, Poland, Slovakia and Slovenia, known as the "Accession Eight".
Two other nations joined the EU on the same day - Malta and Cyprus - but their labour force is tiny and not subject to any potential restrictions.
Along with other EU member states, the UK had a choice. It could either open its doors to workers or use restrictions for up to seven years.
Between May 2004 and June 2006 447,000 people from the Accession Eight registered to work in the UK.
The government estimates that if self-employed people who do not need to register are included, the total is nearer 600,000. We cannot say whether all or just some of these 600,000 workers are in the UK at the moment.
Anecdotally, we know many workers come for short periods - but others certainly stay for a lot longer.
Over the two years, the trend has been marginally upwards. In the first quarter after accession, 42,000 people came to work in the UK. The peak so far was the summer of 2005. Between April and July of 2006 a further 51,000 people applied to work in Britain.
By far and away the largest group of people coming to the UK has been the 264,560 Polish workers. They make up six out of every 10 Eastern European workers in Britain.
The next largest groups are thought to be Lithuanian and Slovakian. The smallest groups are Estonian and Slovenian.
While the government massively under-estimated the numbers who would come, experts advising Whitehall did at least correctly predict what types of workers would come.
The expectation was that those who would make the trip would tend to be younger, tallying with recognised economic migration trends.
Four out of 10 of the workers who have come to Britain have been under 24. A massive 80% have been under 34.
After that age, the numbers drop off steeply, almost certainly because people settled with families are less likely to move than those who are single or childless. This is a key factor to watch for the future.
WHERE DO THEY GO?
The most noticeable element of the Eastern European phenomenon has been where they have been going for jobs.
Historically, migrants to Britain went to the areas where there are labour shortages such as the northern industrial towns or big cities. That means that socially, people expect to find ethnic minorities in these areas.
However, this time around the destinations have been more varied as workers have gone to entirely new areas short of labour.
The early signs of this were clear in the mass arrival of Eastern European and Far East manual labour into agriculture during the past decade.
This has meant that areas of the country unfamiliar to large-scale immigration, such as East Anglia and south-west England, have experienced it for the first time.
This trend has continued. The latest available figures show that unlike during other periods, London is no longer the top destination for migrant workers.
Anecdotally, some employers and local authorities think that a key factor in where people turn up may be the growth in no-frills airlines into Eastern Europe from regional British airports, meaning employers looking for cheap and temporary labour can use agencies to bring people in more quickly than before.
WHAT TYPE OF JOBS?
The government has stressed that Accession Eight workers have been filling what it says are gaps in the labour market, particularly in near minimum wage industries such as food, catering, agriculture or manufacturing and production.
The reality is far more complicated.
Factory workers comprise 37% of the total number of workers over the two years, but many workers have gone into administrative, business and clerical jobs, alongside the expected influx into the catering and hospitality industries.
Transport has seen some substantial numbers - 12,000 workers over two years. Some 16,000 workers have gone into construction.
Some 97% of registered workers were found to be working full time and the majority, as expected, were earning on the lower end of the scale - between minimum wage - currently £5.10 - and £6 an hour.
However, half of the workers were in temporary employment, indicating how many of these jobs tend to be found through personnel agencies working for companies asking for flexible workforces.
A SOCIAL IMPACT?
This remains one of the most controversial areas of migrant working because it is very difficult to calculate the costs on the state compared with the benefits of taxes raised. However, we do have some figures on benefit take-up relating to the 447,000 registered workers.
According to the government, the numbers who have sought benefits and housing support have been "low".
Over the two years, 5,943 people applied for Income Support and the Jobseekers Allowance. Only 768 were deemed eligible for consideration.
The figures also show a demographic shift taking place among the workers. The number of workers with children in the country has doubled since accession, albeit to less than 5,000 as of June 2006.
This indicates that some workers who want to stay are probably bringing their families into the UK.
Some 27,000 workers have been allowed to claim the basic universal Child Benefit (£17.45 for the first child).
Furthermore, 14,000 workers were approved for Tax Credits, the system that recognises families in low-paid jobs.
However, the take-up of council houses has been very small indeed, almost certainly reflecting how stringent the requirements are for getting onto the waiting list.
As of June 2006, 110 council homes across England had been let to Accession Eight workers - representing 0.04% of the total number of available homes.