I'm thinking of going from Berlin to Krakow by train, possibly night train. Now that Poland is in the Schengen zone, what's it like at the German-Polish border? Do you need your passport, is there a control by border officials, what are the train conductors like?
Also, if you know, I read that you can't get a night sleeper anymore for just one person, you have to book the whole sleeper as a group. True?
I'm not sure the way it is when you go by train. I guess there is no control at all. There should not be. I cross German border by car quite often. If you are an EU's citizen, it will be enough if you have your ID. Otherwise, you'd better take your passport, just in case...
Have good time in Poland
I did warsaw to berlin and didn't have any problems atall, i think they just walked on the train and you had to show your passport. its all inside the EU so if you're valid to be in poland and your valid to be in germany it'll be allright. The only thing i'd say is that i did an overnight train from budapest to krakow and that was a real pain as they wake you up to check your passport at whatever time it is you cross the border, so didnt get a whole lot of sleep as there were 4 checks on that one :S