I'm in. I haven't timed myself yet, but I doubt I have ever managed more than about 30 secs for a classic plank. I was told I have good form in a plank during a circuits class last week, which incidentally nearly killed me.
I'm setting myself the goal of achieving 1 min 30 by Christmas.
F 5 ft 3. HW: 196 lbs. Primal SW (May 2011): 182 lbs (42% BF)... W June '12: 160 lbs (29% BF) (UK size 12, US size 8). GW: ~24% BF - have ditched the scales til I fit into a pair of UK size 10 bootcut jeans. Currently aligning towards 'The Perfect Health Diet' having swapped some fat for potatoes.