Is the question asking about positions in the religion or is it meaning in the political sense of the nation?
In either case women did hold high positions in the historical beginnings of the Islamic movement. Historical records have shown that Muhammad himself consulted with women and took their advise seriously, even appointing one female head of her household. Women did stay in the background for the most part, but in the Sufi circles women were teachers, spiritual mothers and even would inherit their fathers spiritual secretes.
Even though women never held any religious titles they were appointed to high political positions. One well known women holding a high position was Khayzuran. She governed the Muslim Empire under three Abbasid caliphs in the 8th century. Many other women also governed over the empires through time.
So should women be given leadership roles in Islam? The answer is yes if following the old historical traditions of Muhammad. Holding a leadership position in the religion such as teacher is not the same as holding a title of the religion but none the less it is a position of leadership. Governmental leadership also being historically done should also be considered in modern times.
I might be completely wrong, but I always thought that Islam was pretty clear that women were not supposed to rule over men. It might just be complete ignorance on my part, but if women were to run Islam than I personally don't think it would be Islam anymore. Please correct me of I'm wrong and may God bless.