[jamesbritt]

"StackOverflow is great to see if a person can communicate ..."

... on StackOverflow.

Meanwhile, the great bulk of programmer communication is happening on blogs, mailing lists, and IRC.

You're very right that written and verbal communication is important, but you have to look in the right places for it.

[jrockway]

The reality is that many people cannot communicate anywhere, so if they are writing good stuff on Stack Overflow, they are probably going to have some ability to explain to their team how their code works. (But it also means that they are the type of person who is happy to waste an hour replying in detail to some dumb person on the Internet.)