over here in our country we get the impression that the USA wants all its countrymen and women to be extroverts and entrepreneurs.
Here, in our country, it is assumed (and wrongly so) that if you don't share your thoughts and opinions especially in group situations, you are not smart. Its very wrong but it happens. Just because one has verbal diarrhoea, doesn't mean one is more intelligent. All that indicates to me, is that, that verbal person, loves to be the centre of attention and could also be a dominating personality.
However in saying that, joining some kind of speech giving group, like Toastmasters, could build up your confidence and experience in holding your own both verbally and bodily in a group situation. I bet your closest freinds can't get a word in edgewise when you are in a one to one situation. Here the "introverts" excell. You know who are introverts? Doctors, surgeons, psychologists, psychiatrists, artists, some musicians.....there is only one of you and you are a treasure to be shined. Remember that!