If BB was a brand new concept in television how would channel four use today's available technology to engage viewers?

When it was first launched, they had the live stream on the Internet, which was a really big innovation.

Technology has progressed immensely, what would they be offering now?

The exact same as C5 are doing right now.

Lets not pretend C4 are some sort of up-market channel. You only need to watch Naked Attraction and Sex Box to see they are all about sex too and that their future plans include a lot of sex. C4 was the reason BB is what it is now, they started the trashiness... well BB was always trashy ever since BB1.

Even their shows like Eden which was supposed to be a "early BB show type" as described and expected by many people, was just as BB is now.

I am sure the usual twitter and facebook interactions would play a part, and i am sure Ch4 will try to grap all those YouTube stars instead of reality "actors".

The producers allowed arguments to get VERY heated and only called someone to the Diary Room when a line had been crossed when Big Brother was shown on Channel 4. It seems to have mellowed since moving to Five. I didn't really watch the Celebrity version much when it was shown on Channel 4.

But none of that would exist yet, BB hasn't been launched, there hasn't been any reality TV for the last 15 years. It's a brand new concept.