I'm a Spaniard, I have worked in five different countries in Europe and Latin America. I'm currently settled in the U.K. I have worked as a consultant, as a developer in a "one-product" company and now I´m working as an in-house developer in a non-tech company.
It simply does not make sense to relocate to USA for me. I have had a couple of offers to work in Boston or New York in the last few years and I turned them down. Weak dollar versus euro means that I won´t be able to pay my euro denominated mortgage while living in the U.S. I am free to work anywhere within the European Union, and I have always been very welcomed in Spanish speaking American countries while I would need some paperwork to work in the U.S.
The political climate doesn't help either. I have never been in the U.S. and I realize that T.V. is not necessarily correlated to real life, but every other day you get news about some guy who was traveling to the U.S. for some perfectly legitimate reason, with all their legal documents in good shape and gets detained at the border for 30 hours, their families are not notified and they are not allowed to drink, eat or sleep.
On the other hand, I personally know some people (about 15 persons) who travel frequently from Europe to the U.S.,for both professional and personal reasons. They have never had problems in the border. There is clearly a dissonance between my "real-life" experience and my "media-induced" experience. Nonetheless, if I had to travel there, I would be a bit scared... my mother would definitely be very scared.
I really hope that things change. My wife is eager to spend a few years living in the U.S. We won't be going for now... may be during Obama's second term (if it happens) it would be economically feasible (strong dollar) and professionally interesting for me. As anyone with a passion for our craft, I have read countless histories about Silicon Valley, and I think the odds would be better for my own (future) start-up in there rather than in Europe, where bureaucracy and lack of funding make things more difficult.