The Marvel Movies Wiki has released an entry on the Infinity Stones that describes the ones used in the moves. It states that the Tesseract is the Space Stone, the Orb used in Guardians of the Galaxy is the Power Stone, and the Aether is still unknown, but I disagree, and I will tell you why. This is purely my opinion and whatever I say has no pull in the Marvel universe, but I feel like the wiki entry and what Marvel reps have told us about the stones doesn't make much sense. In my opinion the Stones that we have seen so far are Wisdom, Power, and Space. I am basing my opinion on the Stones’ properties mentioned on the comic wikipedia page.
In Avengers the Tesseract should be the Mind Gem, because the Tesseract was giving knowledge to those it was used on. When it was used on Hawkeye, he “knew his next target.” It also allows the user to access the thoughts of others and control them, or in layman’s terms: mind control. In Thor: the Dark World we see the Aether, a power so immense that it could destroy the entire universe, and it would succeeded if not for Chris Hemsworth. I think that the Aether should be the Power Stone due to its ability to decimate entire galaxies into nothing.
Now for the Stone in Guardians referred to as The Orb. This one got me thinking. It was a bit hard to figure out when I first saw the movie, but once I got it, it made total sense to me. I say it should be the Space Stone because of what it did. In Guardians, the Stone would rip apart whatever it touched, including the wielder if they weren’t strong enough to use it. One of the powers of the Space Stone is to warp or rearrange space — in other words, teleportation. What I think is that in order to teleport an object it needs to be torn down into molecules and put back together somewhere else, but someone who can’t control that power (or chooses not to) won’t put the object back together. So the people and things that were destroyed by the Stone in Guardians were really just half teleporting.
The Aether is clearly more powerful than The Orb used in Guardians so, to me, it makes more sense for it to be the Power Stone, however The Aether could be the Reality Stone, bending and twisting the other realms into nothing making a new reality of darkness. The Tesseract I can see being the Space Gem because Thor did use it to get back to Asgard, and in Thor: The Dark World, Stellan Skarsgard’s character Erik Selvig was rambling about other worlds and dimensions after being exposed to the power of the Tesseract.
That being said, at the end of the day Marvel does have the last say in things and what they say goes, and I wouldn’t have it any other way.