It’s a mystery what makes some Facebook ideas take off and other languish. Whatever the secret sauce might be, the recently created You know you grew up in Berkeley when… seems to have it.

The group was started a week ago by Trina Waldron-Hudson and already has ove 2,600 members. That already takes it past previous Berkeley/Facebook phenom Your Mom is So Berkeley, which we first wrote about in December 2009 (and still gets plenty of fresh content). Posts and comments have been flying in at a staggering rate.

They range from the specific (“being a ‘traffic boy’ at Jefferson”) to the historically minded (“Mario Savio making speeches”) to the enigmatic (“you called 644-2424”). Does this group have legs, or is it destined to run out of steam after a couple of weeks?

Lance Knobel (Berkeleyside co-founder) has been a journalist for nearly 40 years. Much of his career was in business journalism. He was editor-in-chief of both Management Today, the leading business magazine...