Don't believe everything you read on the internet. I saw a quote posted a while back on several blogs and on here a few times, BUT it is not a real quote from President Hinckley.
This is the false quote:
"Today many sisters are being called to serve. Many more are preparing to serve. Not because they aren't married or don't have anything else to do, but they have the desire to serve. One reason that the Lord wants more sisters to serve is because within the next generation He will send His priesthood army to the earth. He wants to send choice spirit children to mothers who have been prepared, properly trained, and taught in the gospel. What better schooling can a mother have than the experience and growth she gains through serving a mission?" -President Gordon B. Hinckley
If you search LDS.org for the quote, there is no result. Even if you google search it, it can only be found on blogs. Never on a church website or news site. Also, it can be proven that President Hinckley believed that it was more of a priesthood responsibility and that sisters should not feel obligated to go.