Is being a SAHM a job?

Chelsea Mamma lit the touch paper and let it burn......read her post here.  Is being a Stay At Home Mum (whatever the circumstances) a 'job'??

I know there are many different reasons for being a SAHM, you may have had circumstances forced on you, you may have chosen to give up your job.
No ones life is the same and I am sure there will be many SAHM's who will disagree with me entirely and argue their life is far more challenging than ours however this is MY LIFE I am talking about.   I am making no accusations about anyone else's life  am simply outlining how I see it as a working mum and my experiences and observations on/ with my SAHM friends.