Thanks for the lead in Mirjam ;)

I'm not certain as the importance (or lack there of) of wetnurses in other cultures but in Ancient Egypt they were indeed very important.

Wet-nurses were usually imployed by women who could not produce enough milk (keep in mind that in Ancient Egypt babies were nursed up until about the age of three so quite a period of lactating was need, especially if you happened to be lucky enough to have more than one surviving childer under the age of three) or by women of high birth. The job of wet-nurse was one of the few well paying jobs a women could hold. Usually a family would draw up a contract with the wet-nurse who would agree to feed the baby for a fixed period of time for a certain salary. In the Late period, clauses were often added to the contract that stipulated that a wet-nurse could not ingage in sexual intercourse during her time of contract because becoming pregnant might possibly end lactation making a wet-nurse useless :)

There wasn't any shame attached to being a wet-nurse and in fact during the dynestic period, as Mirjam said, the positon of royal wet-nurse is pretty much the highest positon of influence a non royal women could hope to achieve. They were often pictured in the tombs of their royal charges and were usually the wives or mothers of other high officals.

References: the ever useful "Daughters of Isis: Women in Ancient Egypt" by Joyce Tyldesley