Don Boudreaux at Cafe Hayek on the effect immigration has on jobs.
First, the claim from an anti-immigration organisation :

Because immigration increases the supply of U.S. labor, it reduces wages or makes jobs more scarce for natives.

Seems obvious, yes ? Not so.
Don goes on to note that immigration has been fairly high in the US over the past few centuries, and that jobs and incomes are all way way up.
Something to think about today as all those hordes of Central Europeans are able to come to the UK. It might actually be a good idea to let them in.