My team worked with Lufthansa in updating our FlyNet FAQ (I think we are now on the fourth edition).
The quick summary is that 70% of the long-haul fleet currently has FlyNet and that will grow to just shy of 100% by the time we all watch Dinner for One at the end of the year.
In addition, the 748 will get FlyNet starting in the middle of 2013 and the A380 will get the retrofit towards the end of the year going into 2014.
The complete details are
here.