Mark Zuckerberg, 26 years old and the founder of Facebook, is in the dock, accused by three of his former college mates of nicking their ideas for a student networking site, then called HarvardConnect.com, now called ConnectU. The stakes are high - the plaintiffs are demanding closure of Facebook.
Intellectual property is very difficult online. I'm involved in an internet start-up right now.
We have some great - we think original - ideas, but we've been informed by the patent lawyers that there's precious little we can do to defend them, as we're staking out one of the gold rush areas of the web.
There is considerable overlap in people's approaches - perhaps the stuff of future litigation as losers try to salvage something from winners. But, in the end, the difference between success and failure is not going to be concept, but execution.
This is where Zuckerberg's argument is strongest.
The ConnectU boys complain that he stole their lunch, but Facebook is now the 13th most trafficked site in the world, with more than 30 million users and 15 billion page views per month.
It is rumoured that he has received a bid valuing the company at $2.3bn, rejected because the board thinks it's worth $8bn.
It is a terrific brand, with great applications like The Wall, the "poke" and the simple but extraordinary "gift" section, where people spend real money to send a virtual gift of a rose, a teddy bear, a bottle of champagne to the object of their desires.
I know. It's quite remarkable, but when your friends see your gifts, your trophies, displayed on your page, this says more about you than a skin and your grooviest content ever can.
ConnectU has stayed true to its student stuff and has 70,000 users.
In our business, we are big on ideas. We prize them, celebrate them, award them, and rightly so.
But however the Facebook judge decides, here is a classic case study of how the idea is only the entry stake.
Without brilliant execution, an idea is like a seed in a packet - full of unfulfilled potential, but dry.
Richard Eyre is chairman of the IAB richard.eyre@haymarket.com.