Intelligent Design is said to be a "big tent" which has room to accomodate many different views on how the designer acts to accomplish its purposes. There are, for example, IDers who hold that the designer (who for Christians is the God of the Bible but for non-theists could be a denizen of one of the near infinity of other worlds hypothesized by theoretical physicists to exist in the multiverse) intervenes periodically in time and history to tweak the creation, creating life at one point and then consciousness, and so on. These are called progressive creationists.
There are others who believe that God acted much as described in Genesis, compressing all creative activity into a brief period of time at the beginning. These folks are called special creationists. There is a third group which holds that the designer "front-loaded" the creation into the initial events that triggered the Big Bang. In other words, the initial conditions of the Big Bang which give rise to all the laws of physics and everything that subsequently results, are foreordained in the creative event. These laws and constants eventually, through an evolutionary process, produced intelligent life.
All of these different formulations share two things in common that make them members of the ID club - they each maintain that however life came about it required an intelligent input, and they maintain that evidence of that input can be discerned in living things and in the cosmos. It is essentially this ability to detect the designer's work, by the way, that distinguishes the front-loaders from theistic evolutionists who believe that God's activity does not contravene the laws of physics and that the natural world does not reveal intelligent agency. The theistic evolutionists' belief that God exists is for them a matter solely of faith and that evidence of His existence should not be looked for in the patterns of life. Both the front-loaders and the theistic evolutionists are concerned with maintaining the uniformity of natural law (which is in some ways an odd concern since many of them believe in Biblical miracles).
I don't know who among the foregoing is correct in this matter, but I do think that if it were to turn out that God does not act the way the special or progressive creationists envision one still need not think that His action is located solely at the beginning of creation. Indeed, such a concept of God leads one in the unwelcome direction of deism, the view of God as a distant and uninvolved absentee landlord.
Imagine instead that the progress of life is like a river in a shallow stream bed meandering widely through a broad, flat valley. In mountain valleys in Alaska such rivers are often braided, i.e. they're made up of dozens of rivulets and lesser channels that weave through the valley in an intricate filigree, intersecting with, and diverging from, each other, all the while carrying the water forward. The pattern of progress appears imbricate, convoluted and completely random, guided by nothing but physical laws and forces much as evolution is guided by laws like mutation and natural selection.
But perhaps, just as the course of the water is really determined by the contours of the soil and rock which make up the channels of the stream bed, the flow of life is "embedded" in God. In other words, God guides the flow, it takes place in and through Him, not just at the outset of creation nor only sporadically throughout its history, but rather moment by moment as it wends its way over the course of deep time. God is not just a temporal cause of the development of life but also its sustaining cause. Just as there can be no river without a channel to guide and contain it, there can be no life or evolutionary development without God undergirding, enfolding, and leading it constantly and continuously toward the end He envisions.
Evolution follows the course it does because of the "invisible channels" that carry it ineluctably toward a particular telos or goal. Evolution, especially its direction, is entirely contingent upon God as the river is dependent upon its underlying substrate. Unlike the deistic God of the front-loaders and theistic evolutionists, God is both immanent, or present in the world, and necessary moment by moment, not only for the existence of life but also for its development.
