There are good news about new railway connection to Berlin that is being established in June. Trains will start operations on 6th of June and there will be not one as we expected but two daily connections, although on two different routes.
As first EC Daniel Fahrenheit will depart Gdańsk at 6.00 and go via Poznań and reach Berlin at 13.14. Time of departure will probably change due to ongoing modernization of tracks, it is said that this train will probably depart around 6.45, so journey should take 6h29min.
Another train will be DB Regio, which will depart Berlin at 6.10 and arrive Gdańsk at 12.40, then it will depart Gdańsk at 14.30 and reach Berlin at 20.50. DB Regio train route will be via Gorzów Wielkopolski and Piła.
Now some more good news about prices, PKP said that there will be special offer tickets available for 29€ and 39€ and regular return ticket should cost around 50€. The latter connection should be even cheaper.
This are really good information, especially that airBerlin connection (starting on 25th of March) turns out not to be as cheap as I expected. Right now return ticket costs about 120€.source: gazeta.pl