When Facebook removed the requirement that members have a .edu or equivalent email, many users were aghast — concerned that the community would soon be overrun with old people.

As an old person, though, it’s a whole new way to waste time social network. During my first couple days I only made a few cultural errors and was asked by a younger colleague to stay away from his site.

My original page was overly formal, as I cut and pasted from my corporate bio; since then I’ve made it more personal and inviting. Some other oldsters (full disclosure: I’m pushing 40 hard) find it irksome to add another profile right after they’ve been muscled into joining LinkedIn. I explain to them that while LinkedIn is a grey flannel suit, Facebook is an Hawaiian shirt. If you wear a grey flannel suit to a party on a boathouse roof, you are an ass. If you wear a Hawaiian shirt to a board meeting, you are an idiot. You need both.

The May 2007 issue of Fast Company shows that the greying of Facebook is growing. As of February 2007, almost 1 million people over 35 have joined. I expect that to double each month for the next year.