(PS I do not know whether oDesk charges you for creating a job, if so take those fees off the $40)
oDesk's fees paid by the employer are 10% of the "job".
If you are hoping for a $40 payout, then you probably meant to suggest adding those fees on top of the $40 then?
e.g., $40/0.90 = $44.40 payment to oDesk, oDesk takes the 10% cut ($4.44) leaving $40 to you.
Of course, setting up a fake job listing for the purpose of simply transmitting money is certainly against oDesk's terms of service. There have been reports of oDesk suspending accounts that they suspect of participating in money laundering, though I'm not trying to imply that this type of transaction would be considered to be that.
For the prescribed use though oDesk's list of countries in which they treat the withdrawal transfers as "local currency" (i.e., can do a domestic bank transfer) is interesting as there are nearly no Bitcoin exchanges supporting hardly any of them: Armenia, Bulgaria, Colombia, Croatia, Egypt, Indonesia, Jamaica, Kenya, Morocco, Pakistan, Peru, Serbia, South Africa, Tunisia, United Arab Emirates, and Uruguay.