I suppose it varies between office/department but when I interviewed there 2 years ago I saw nothing but MacBooks.

Those are laptops, which are dumb terminals running Chrome, not workstations. Workstations are Linux.

Most Google engineers use Linux on desktops. For a laptop, you get to choose between a Mac and a PC Laptop (running Linux as well).

You get a choice when you join: Macbook Pro, Macbook Air, or a couple of varieties of Thinkpad running Goobuntu.

How about Macbook Pro running Goobuntu?

Frowned upon for supportability reasons, even if you made it work with all the corp management stuff.

But like drbble said, laptops for engineers are mostly for Chrome, terminals, and NX/VNC sessions, since you can't code on them directly.

So they're exclusively thin clients presumably for security reasons? Is that the take away? Sorry if I'm being thick.

I wouldn't say they're exclusively thin clients; you can run more or less whatever apps you want (I use Omnifocus, Graffle, bunch of other stuff). But source code isn't allowed on laptop HDD's, so most engineers develop remotely on their workstations via SSH/remote-desktop.

Possibly because all of their products also have to work on OS X. Giving every developer a MacBook makes testing those products easier.