Is wireframing an important step in web design?

Do you employ wireframes as part of your web development process? If you’re like me, you might sketch out ideas on paper. Or at other times I’ve gone into a graphics program (Photoshop) and moved labelled blocks around to approximate where this or that page element should be. I’ve also used OmniGraffle (disclosure: I’m on Macs) — though now I’m tending toward Curio to collect all project inspirations and elements in one place.

But there’s a goodly selection of SaaS sites that provide, for free or for a fee, the opportunity to create ultra-simple diagrams of how you envision the web site (home and sub pages) laying out: logo sized thusly and over here, accordion element there, list of recent tweets over on the right, etc.

Grace Smith is a true Twitter resource (recommended follow for web designers) and in her review of Mockflow has generated some good discussion about wireframing alternatives (see comments).

So, how do you handle your wireframing and/or what software or service would you recommend?