If you are into changing the world by willing society forward with ground breaking [insert impressive thing here], your talents would be wasted at Facebook (despite Mark Zuckerburg's stated belief that fb can change the world by allowing people to share with each other and understand each other better).
I think they are solving complex problems (which is respectable) for a largely trivial mission.
Would you say that Google does not require first rate engineers? I would imagine that the most important part of their operation is scaling. They have admitted themselves that the difference in search results returned by the search engines is virtually nil, so their strategic advantage is really being able to support a lot of users (for the search engine as well as other internet services).
The first time that I wrote a long message and saw the message window expand, I jumped with excitement. It was pretty awesome to find a new feature one day that I didn't expect and never would have thought to ask for.
Maybe we are using "meaningful contributions as a metric". Here is a page of some of their contributions: http://developers.facebook.com/opensource.php
I am just reluctant to say that engineers at fb are not first-rate. Are we saying that they are second rate?
I agree that fb is the toy analog in the web app world but does that mean that the engineers who banged out the PS3/XBox 360/Wii are second-rate?
That's exactly the problem that I had with my comment. They're only not first-rate if you expect every engineer to be literally genius. That's too much to expect for any one company. So first-rate is as close to accurate a description as you could get.
I've always found it odd that not many hackers that I've met really get into discussing video game mechanics: either hardware or software. It's odd because video games are what got me into programming software, and the only time I've ever felt like making hardware it was designing imaginary game systems.