Short form: wow. Long form: Unless the trailer is being purposefully deceptive, a lot of the grandiose hints and guesses on the web appear to have been right! Don't knock yourselves over patting yourselves on the back, fellas. The Goblin, Sandman, creeping dark oozy costume. Only anyone who thought the Lizard would make it in will be disappointed. (Well, also those who were expecting the Beetle).
As someone whose main exposure to Spider-Man was through (one of) the animated series, I am stoked. That series introducted Venom through a three-episode story that left such an impression on me that I bought the DVD. The downside of these episodes is the low-budget but still adequate quality of the animation.
Here's a summary of the important points: a moving alien ooze, which in reality is a sentient symbiote, makes contact with Spidey at a space shuttle crash. It acts as a dark but shapeshifting costume that obeys his thoughts while also taking the initiative to be protective of him. More importantly, it increases his superpowers to an intoxicating degree. Peter revels in his newfound majesty, but at the same time his moods and attitudes take a turn for the worst. New levels of aggressiveness, selfishness, and peevishness change his actions and inner monologue. Only when he realizes how he is alienating all the people in his life as Parker, and how close he comes to needlessly pulverizing his supervillain opponents, does he force the costume off him using loud noise. The costume finds a host who happens to hate Spider-Man with as much passion as it does. The two merge to become Venom, a villain with all the power that Spidey had when he was wearing the costume. Meaning anything Spider-Man can do, Venom can do better. Venom commences a systematic campaign to scare and torment both Spider-Man and Peter Parker. In the end, Spider-Man wins by luring Venom to a shuttle launch, using himself as bait. The noise weakens and forces the costume off its new host so Spidey can attach the symbiote to the shuttle and wave it goodbye.
I think the reason the story is so compelling to me is because the symbiote is a metaphor for the use and abuse of power/pride. People can flaunt it, try to use it to lord over others, pursue it desperately for the sake of survival, or just fall in love with it to the expense of all else. Unfortunately, power can also corrupt the user, and leave him or her alone with a resulting mountain of regrets. Since the power-corrupted can only view others as below him or her, there can be none of the healthy relationships that form among equals. Although power is a potent drug, seeming to offer freedom from fear, it's nothing without morality to moderate it so it doesn't devour itself.
If the movie taps into this same theme for the symbiote costume (the destructiveness of: 1. power, 2. the exercise of power, and 3. the pursuit of power), well, here's a preemptive I told you so.