The ten commandments¹ as described in Exodus can be considered as two distinct sections, with a connecting bridge. Commandments 1-4 concern our relationship with God, commandments 6-10 concern our relationship with one another, and commandment 5, Honour thy father and thy mother bridges the two concerns, indicating a hierarchy of reverence: first to God, then to parents and finally to all of humankind.

Of commandments 6-10, murder, theft and bearing false witness (lying under oath) remain crimes today; adultery, while only a crime in certain cultures is certainly considered immoral and generally unacceptable in all others. Covetousness, the last commandment, and the one quoted here, is neither a crime, nor considered unacceptable. Indeed, it is encouraged. It is encouraged under the belief that desiring what others have is a step towards bettering oneself. In a culture where worth is measured not in deed but in possession it becomes desirable, even necessary to always want more than we have.

While commandments 6-9 are moved by retributive justice, the last commandment is moved by distributive justice, and has remarkable similarities to the communist ideal as expressed by Karl Marx: "From each according to his ability, to each according to his needs." By coveting the goods and qualities of others we are essentially denying God. Distributive justice tends towards an equitable society. We treat others justly because in creating right relations with one another we may be in right relationship with God.

"The people of God are a community in which the welfare of each is the concern of all. We cannot view each other as objects to be used, but as fellow heirs of the saving acts of God." ²

The last commandment is not about following rules, but about building character. As we desire that which we have not we'll tend towards unhappiness. As we appreciate what we do have—and do this in community with others—we'll tend towards a collective joy. Gratitude is the antidote to covetousness.

¹ There are not actually ten clearly delineated commandments in either Exodus or Deuteronomy, and of those listed (somewhere between 9 and 13) different traditions order them slightly differently, most using ten as a simple number with which to categorise. The corresponding Wikipedia article goes into some depth on this.
² From The Ten Commandments for Today's Christians, an anonymously-authored paper