See the 'Recognition' section in "Great Hackers" essay, http://www.paulgraham.com/gh.html: "So who are the great hackers? How do you know when you meet one? That turns out to be very hard. Even hackers can't tell."
Sadly anti-immigration and/or anti-capitalism feelings are also strong in many EU countries which hampers this movement. I wish the UK could make more of our draw.
Where?
AFAIK, there's no problem with freedom of movement for employees in the EU, not even to/from the UK. The only issue is wages; London startups pay really shitty salaries (£40-50K). Berlin's aren't much better (lower than London, but in a much cheaper city). It's the exact same problem as in the US - the salaries just aren't high enough to justify moving to and living in an expensive city.
But not sure that reforming H1-B will be an easy battle to fight. Many of the companies that have large H1-B workforces are also very politically connected and stand to lose a lot of money.