Nonsense. Cyrillic was never used in Poland.
I was in school at the time of the "Polish Millennium" and I was taught that the King of Poland at the time (Mieszko?) made a conscious effort for Poland to use the Latin alphabet and follow the Roman Catholic Church. He did this for political and social reasons. He wanted Poland to become Westernized. I thought that the previous alphabet was Cyrillic as that what accounts for the apostrophe's over the Polish letters and I thought I read something as much over the internet but I can't find it, so I might be wrong (can it be?).