Even the well-off engineers of Silicon Valley fall for the offer of a free lunch, it seems.

In a phenomenon dubbed Lunch 2.0, workers in the Valley are descending on other companies for free food and the chance to satisfy their appetite for making contacts.

It started with four men trying to sneak into companies such as Yahoo and Google to sample their free gourmet lunches.

But the idea has been picked up and developed. Several companies have begun inviting all- comers for a free lunch.

Except, of course, it is not free. The lunches are partly about networking and eating, but they are also about pitching products and sizing up talent.

In the latest example, more than 100 people turned up for lunch at the offices of Ning, a social networking web platform, in Palo Alto last week.

They were treated to sandwiches, salad, biscuits – and a presentation by Gina Bianchini, chief executive.

“It’s an opportunity to give back to the area and the people who are working here,” she said. “And we are hiring at the moment.”

David Kellogg, a Yahoo technician and one of the co-founders of Lunch 2.0, said: “There’s a business side and a food side to this. Companies want to get their message out and we will all go back to work and blog about this. I’m widening my network and finding out what’s going on in companies.”

He rates lunch at the LinkedIn social networking company the best so far.

“Most of us engineers make enough money to pay for lunch but the lure of free food brings out the student in us,” Mr Kellogg said.

Google has yet to offer an official invitation but Lunch 2.0 is spreading to other cities, including Los Angeles and Seattle.

So far, though, no-one has suggested a Washing-up 2.0.