From another perspective

Dive into Mark has an interesting post, "The first thing we do, let's shoot all the copy editors."

He wrote a book for programmers that is now with the copy editor:

Now the copy editor is wielding her virtual pen and striking through every word I’ve ever written. Incorporating her revisions is simultaneously humbling, enlightening, and mind-numbingly tedious.

He then lists what he's learning from her notes: that vs. which, placement of only, etc.

But the comments following the post are good, too. Take this one:

Admittedly, when you’re publishing a book it’s important to have your copy edited (for accessibility’s sake, if nothing else), but I’ve always been fond of this quote from my linguistics lecturer:

“If anybody ever tells you that you’re using the language incorrectly, just yell ‘prescriptive grammarian!’ at the top of your voice and all the linguists in the building will run over and surround the guy… and then they’ll rough him up”

The is no such thing as correct usage; only common usage and prescribed usage. I find it liberating.