The Market itself is open to lots of countries, but many of these countries don't have support for paid apps yet (only free) which is very frustrating.
Actually I seem to remember that the only countries in Europe who are allowed to play are Germany, France and the UK.
It is being frustrating because it could be fixed tomorrow - the issue is that Google is using its own payment system (google checkout) instead of a real payment system such as paypal.
If you ask me, it borders on what Microsoft did with IE and netscape in the nineteens.