At Plug2010 I talked to Onno Bakker co-founder from Ebuddy. 30 millions users chat monthly with their client. More then 150 million Chat/month with 15 billion chat lines (how many hours is that. In q4 2009 they were profitable by adding advertising. Detail: 10 million people use the mobile client but they do 50% of traffic. At the end of 2011 Android will be bigger then iphone.