The 777 appears to have a much larger satellite antenna on the roof than I've seen on the A380. It seems to be quite incredible at holding on to the signal even when switching from one satellite to the next. The 380 is a much more disappointing experience as far as speed and downtime. I've got 6Mbps download speed on the 777.
The crew connected feature is for future technology such as pilot and purser tablets. Theoretically your netbios name may be visable in the logs 'Joe blogs iPhone' for example. Also if they really wanted to be clever they could see the time stamps when you connected to company email or other company apps. But then we're really into the tinfoil hat territory..