The key is to have no involvement from marketing and other executives, other than the engineering department. The approval process should be very very fast and easy. For example, just the CTO needs to approve and he does this almost always, and within a day.

Even the slightest friction makes the engineers not want to bother.

We've made a pretty successful engineering blog at blog.doit.com. I've published more there by far than in any comparable period of my career