For some, that might mean weekly or even daily updates, or just when an important milestone is reached; for others, less is more — in *my* experience, anyway. It's worth asking, early in the relationship how often and how (voice, email, IM, smoke signal) they'd like to receive any updates. YMMV.

The reason I mention it is that it used to drive me NUTS back in my days as an editor when a FLer needed constant handholding or updated me on silly stuff.

What? Since when is wanting to be paid unprofessional? Quite the contrary, I'd say (unless the invoice had just been sent out).

I wish I'd saved the URL. It was one of those posts that someone tweeted or retweeted, so I honestly couldn't say where I saw it.

The biggest mistake freelancers can make is agreeing to do a job and blowing it off, like you described. Of course, I've landed a couple of quick jobs thanks to irresponsible types who left my editors in a lurch.