Some points about Jacob from the Bible that may be relevant to Lost.
Jacob was the son of Isaac. He was not supposed to be Isaac's heir, however. At his mother's bidding, he tricked Isaac into giving him the blessing that was meant for Esau by making himself seem hairy (Isaac was blind). The idea of stealing the blessing seems to play in Lost, where there is great competition between Ben, Widmore, and Locke for the position of favorite of the island.
Jacob had four wives and had 12 sons and one daughter. He is known for spawning the 12 tribes of Israel. Parental issues seem important in Lost, and the two people Jacob apparently is hanging out with in his cabin are both notable parents, and are son and daughter themselves. The biblical Jacob is also the great-great-grandfather of the biblical Aaron.
Jacob's son Joseph was sold into Egyptian slavery by his other brothers, but wound up working up the ladder of favor among Egyptian nobles by his ability to interpret dreams. Eventually Jacob reunites with Joseph as a result of his sons going to Egypt during a time of famine. After reuniting, Jacob lives out the rest of his life in Egypt. Egyptian themes seem to be getting more and more important in Lost. We've seen hieroglyphics everywhere, a drawing of a sphinx, and a very Egyptian-looking mysterious statue.
One possibility is that Lost's Jacob is supposed to be the Jacob of the Bible. This doesn't seem very likely to me, though, but I'd be willing to bet there will be some thematic connection.