Currently in Australia it is down to the individual's contract, but the Australian Government is introducing a paid parental scheme in 2011 where any employee who has a child will be eligible for up to 18 weeks at the minimum wage.
Some employers currently offer quite generous paid leave in Australia, but I can't think of any that employ pilots (perhaps some QF or J* people could add to this). I don't recall reading anything about it in the recently released award.
As for foreign operators, sorry but I have no idea. They would be bound by the laws of the country in which they operate.