here is a very interesting article about Lithuanians and Poles by Virginijus Savukynas (in Lithuanian). Assuming that the article is correct - it is amazing to me how the two nations were intertwined say 120 years ago as compared to now.
1. here is a good article about Lithuanians and Poles from 15min.lt
2. Wikipedia provides is a sign similar to the one provided in the article. If one would translate it from Russian, it would read "Speaking Lithuanian Strictly Forbidden"