by Barbara S. Peterson

You can knock 20 percent off all JetBlue flights departing through October 31--but you have to book by midnight tonight. The quickie air fare sale is in honor of @JetBlue reaching one million followers on Twitter.

JetBlue claims it's the first airline to reach the exalted one million mark. No one's come forward to dispute that, but airlines like American, Delta and United--with far more passengers than JetBlue--are aiming to catch up soon.

United, like JetBlue, already has regular weekly sales for its Twitter followers. United calls its deals "twares" and JetBlue's are "cheeps". Oh well, no one said they had to be brilliant.

So is the JetBlue sale a really big deal?

Here's what cheapflights.com wrote: "We did a quick search for flights to just about anywhere and the promo works. The only blackout dates are October 9 and October 12, 2009 (Columbus Day weekend)."

Agreed. We did some poking around, too. To book, go to jetblue.com/millionth.