This is all vaguely coming from things I've been trying to figure out for my Big Bang, so bear with me if it's not so great at coherency.
We know that Sam's got some awesome psychic powers and that he got them when Azazel dripped his blood into his mouth. We also know that he appears to have powers that the demons on the show (Meg, Lilith, Ruby, Alastair) don't have - seeing into the future, pulling demons out of host bodies, telekinesis.
The characters on the show have shown that they believe that Sam's powers are demonic in origin and we fen have, from what I've seen, gone along with this theory. (I, too, am complicit. I belong to
sammessiah, where Sam is Demon Jesus all the time, and have written fic from that view.)
However, I would like to host a new idea: Sam's powers are angelic.
Now, even if they aren't angelic in the way that Castiel and Uriel are angelic (though I will argue for that in a moment), I will hold firmly that they are not demonic in the way that Lilith, Meg, and Ruby are demonic. If Sam's powers are demonic in type or origin, it's on a whole new playing field.
We've learned a fair bit about Hell in the past two seasons. People become demons when they're stuck down there for too long. Ruby was once human. Alastair was, presumably, once human (after all, he's made at least one reference to WWII). Lilith, everyone's favorite Big Bad, was once Adam's first wife, if we're going by traditional mythology. They're all human.
I'm going to go out on a limb and suggest that fallen angels, though they clearly have a place in Supernatural mythology, aren't in Hell. Lucifer clearly isn't in Hell. Azazel, Sam's second "father," wasn't in Hell. Ruby, who had spent enough time in Hell to become a demon, was terrified of Castiel because she'd never seen an angel before the beginning of season four. Hell is, for Supernatural's purposes, other people. People turn people into demons. (Now isn't that depressing?)
However, Azazel dripped his blood into baby Sam's mouth. Azazel is a Grigori - a Watcher, from the same rank of angel (according to certain theologians - obvious this is all dependent) as Uriel. Azazel appears in Leviticus, where the Israelites in the desert give two goats - one to God and on to Azazel - for atonement for their sins. He also features heavily in the Book of Enoch, where he teaches humanity the art of war and sleeps with human women, producing the Nephilim, a monstrous half-human half-angel race that also appear in Genesis, specifically in the story of Noah.
Sam's powers come from the Scapegoat, from a fallen angel. He is not already partially turned demon. He is something more than human - something more than Ruby or Lilith or Meg or Alastair. I would argue that Azazel's blood brings him close to Uriel and Castiel (or Azazel and Lucifer) than to Ruby or Lilith. He's got angel blood, even if that angel was fallen.
Sam powers are different than demon powers, that we've seen. All of the psychic kids were different from demons, actually. Sam can see the future, just like Ava could. Andy and Ansem could command people with their voices. Max had telekinesis and Lily could kill with her touch. Scott could harness electricity. Jake had super strength and developed Andy and Ansem's power as well.
These are pretty specific powers - and nothing like anything we've seen demons do. Demons seem to have some telekinesis powers, but, at least to my eyes, it appears to manifest differently.
Beyond this, I'd like to bring Anna into the equation. Anna, too, was angel and human. She also manifested her powers in a way that is similar to the psychic kids - she didn't know what was going on, she didn't understand, but under pressure she could save herself. When she regained her grace and blasted everyone, her eyes went yellow.
And Uriel thought she was an abomination who needed to be destroyed. (Hint: Who else does Uriel think is an abomination who needs to be destroyed?)
I think it would be kind of amazing if it turns out that Sam's powers are truly angelic and he's some kind of bastard half-breed - that Azazel found a way to get around the Nephilim problem. It would be truly ironic if, after working with Ruby, a demon, and trying to fight his powers because they were evil, it turned out that Sam has more in common with Castiel and Dean has more in common with Ruby.
In any case, I want to know where the fallen angels hang out. It's obviously not Hell. Where's Lucifer? Did Azazel have buddies? Is yellow the color of an angel's eyes? How did Azazel drip his own blood into Sam's mouth - do high ranking (fallen) angels get their own bodies a la Good Omens?