I think the main issue here revolves around one's understanding of the term 'fluent'. Many people seem to think that 'fluent' is a synonym of 'perfect'. To my mind, it is not.
Someone on the last page posted something to do with being competent in a foreign language but struggling if someone mentioned a certain term relating to science or a specific sporting activity, and saying that this would indicate a lack of fluency. This is completely untrue. How many of you have ever come across a word in English or your native tongue that you didn't understand, even as an adult? All of you, I imagine. I consider myself erudite and articulate, but I know nothing about science or sport, so I lack lots of English vocabulary in these fields. So by this definition, I don't speak ANY language fluently! What an absurd notion. Of course my English is fluent.
I've studied Spanish for four years and lived in Mexico for a year. There is no doubt in my mind that my Spanish is fluent. It's a little rustier now than when I lived in a Spanish-speaking environment, but it's fluent. I can communicate in accurate and eloquent Spanish in a variety of situations about most topics without much strain. There are, of course, plenty of things that I don't know how to say in Spanish - if I had to talk about Olympic events I wouldn't know how to say "shot put" for example. However, I would have no problem communicating the idea...I'd just say "Esa disciplina de los juegos olimpicos donde tiran una pelotilla hecha de metal..." (That sport where people throw a little metal ball).
I think fluency is really when you find conversing and using the language in most situations second nature. When you don't have to translate mentally from your mother tongue. When you can manipulate the language, and don't have to rely on set expressions.
I would even argue that grammatical accuracy and accent aren't that important when it comes to fluency. For example, if an articulate foreigner spoke English with ease and said something like "We basked in the glorious sunlight which last two hours" - would the grammatical error render them "unfluent"? I'd argue not. Many English people's knowledge of English grammar is fairly shocking at best, let's face it.
To my mind, fluency is fairly simple. Can you communicate your message effectively in a foreign language at a normal pace and without struggling too much? If so, you're fluent to my mind. Not necessarily elegant. Not necessarily perfect. Not necessarily articulate. But fluent? Yes.