The reasonable side of the brain would have to say: what's the worst posssible outcome for each option? Deciding what to do based on the best outcome is a weakness we all have to fight though
Since the worst possible outcome of taking on the summer contract is to find yourself unemployed with kids and mortgage in November, it's probably best to decline the offer.
I'd say wait one more year. The possibility of a double-dip recession is still there, so getting another job after your summer stint might be impossible. By 2011 the picture should be clearer.
P