As you already know (I hope you know), DebConf11 will be held in Banja Luka, Bosnia and Herzegovina and according to this LINK, official dates are:
DebCamp: 25th – 31st July 2011
DebConf: 1st – 7th August 2011
DebCamp: 17 – 23 July 2011
DebConf: 24 – 30 July 2011