Usually there is a ban on sale of beer introduced in 2009 for security reasons, but a special new law concerning beer sale in the stadiums will come into effect for the time of the Euro 2012:
1) At stadiums it will be possible to buy light beer only(4.5% max). But unfortunately for some "high-risk matches" the sale of beer will be prohibited. The conditions for those "high-risk matches" have not been specified yet.
2) It is expected that there will be a limit on the amount of beer that can be bought by one person. Probably in the form of stamps on the hands of the fans, which should show how many beer the person already bought.
3) People bringing their own alcohol can face arrest and/or a fine of not less than 2000PLN(500Euro)!
I guess we will just have to wash our hands more regularly this time around.
Edit: The Polish Senate voted against amendments to the Law on security at public events, which permits sale of low alcohol drinks at football matches, including matches during Euro 2012.
This means a total ban on consuming of alcohol drinks in sport arenas will operate during and after the EURO2012.
Edit2: During next year’s European Football Championships in Poland and Ukraine there will be a total ban on smoking in all stadiums. It will not be allowed to sell or promote tobacco in the stadiums and their surroundings.