Let's not forget about president Woodrow Wilson and Paderewski's concerts around the world as factors contributing to the regained independence.
There are many squares, streets named after Wilson and FD Roosevelt around Poland - and not because they were renamed from Djerzhynsky Square, but they have existed for decades now.
Proof:
Google "ulica Wilsona" Wilson Street: Warsaw, Czestochowa, Bielsko-Biala, Opole, Lodz, Knurow, Tarnow, Radomsko, Brwinow, Chojna, Jastrzebie Zdroj, Zambrow. Cities and small towns.
A local portal from Zambrow explains who Wilson was (though everyone should know from school), and that the US ambassador visited Zambrow in 2007, expressing satisfaction at so many places in Poland named after Wilson.
http://www.zambrow.org/aktualnosci/strona.php?strona=artykuly_pokaz&id=3239
Roosevelt Square - one of the main squares in Olsztyn:
http://pl.wikipedia.org/wiki/Plac_Franklina_Roosevelta_w_Olsztynie
History of Roosevelt Street in Poznan (named so from 1945):
http://www.kobidz.pl/app/site.php5/getFile/372
And many Roosevelt Streets, some Wilson Squares all around Poland. But most (all?) of them had those names also under Communism.
However, the Wilson Square in Warsaw was renamed after the Commune de Paris in Communist Poland:
http://pl.wikipedia.org/wiki/Plac_Thomasa_Woodrowa_Wilsona_w_Warszawie
http://en.wikipedia.org/wiki/Wilson_Square