From my interactions with Facebook engineers, they certainly have the belief that they are changing the world and for the better. Ascribing purely monetary considerations to their choice to work at Facebook rather than Google does them a big disservice.

It is also the case that Facebook is still quite small compared to Google. I am sure that many people feel that they have a better chance of having a larger impact at Facebook than they would at Google. The appeal of being a major factor at a dynamic and growing startup rather than another cog in a big machine will always shake people out of companies that get to a certain size, no matter how well that big company has managed to sustain an innovative small company feel (or its PR to that effect ).

The more interesting ‘signal’ would be related to Brandon’s 3rd point:

How many of those 40 did not receive pre-IPO Google shares.

If I had to make WAG I’d bet more than 80% did not.

It seems the pre-IPO Xooglers that have left are all doing something new on their own. And a majority of the Xooglers that transition to FB are looking for that IPO windfall that is more likely to happen sooner by going to FB than starting from scratch.

Not that I’d blame them, it looks like a quicker path to multi-millions with less of the start-from-scratch headaches and hazards. But one must look a that and say, what are the real motives in these instances and perhaps discern from that what is driving the reason for them doing what they’re doing.

Before Google went public the company was filled with people who truly believed they were changing the world and for the better. That belief still held after the IPO but that was a more common denominator, even after the IPO and through much of 2007. These are people that will give you more for your money any day over someone that’s working for just for the money.

This is likely to be the difference in the real economic success between Google and Facebook.

J

1) They are close geographically, you don’t have to move.
2) You’re guaranteed to be working on a “sexy” product.
3) They’ve gotta IPO sometime, right?