(NOTE: Some religious content ahead. )
My own faith holds that before we came to earth, our spirits existed in some pre-mortal state of being with God, and that upon our birth a veil of forgetfulness descended over our minds to cause us to forget that previous existence as part of our earthly testing (in part, to see how well we would do what was right, even when we believed no one was watching). Because of this belief in that veil of forgetfulness, I find it interesting -- perhaps significant -- that the specifics of our dreams so often fade from our minds when we wake up. (In fact, the only way to keep the details of most dreams clear is to write them down as soon after waking as possible.) Perhaps the veil was temporarily lifted in sleep and is allowed to fall over our minds again as we wake.
By this I'm not trying to suggest every dream has equal significance. Sometimes they're purely random nonsense, as when you find yourself in a house made of cheese with a roof of Branston pickle, and tiny pteronadons keep flying through the parlor to deliver packets of dental floss. (This dream's message: stop eating pepperoni pizza before bed.) Sometimes the dreams you have are heavily and obviously influenced by a movie you just saw or your latest bedside reading material, and you can tell there isn't anything significant about them.
But then there are other dreams. I know of at least one person who has, in dreams, had an important and very lucid conversation with a parent who had died. I know of two people who had the same richly symbolic dream, independently of each other. And I had a significant dream about a month after my father died, which was a great comfort at the time. Without going into it too deeply, I'll just say the symbolism of the dream was personal, very understandable to my twelve-year-old mind, and helped me remember that although my father might be dead, he wasn't gone for good -- that our family was still intact and had the power to remain so forever. It provided a lifeline at a time when I most needed it.
So: does God talk to us through our dreams? Personally, I think He does so on occasion. (Certainly it would seem to be the only time of day when we're prepared to give Him our undivided attention, no?)