Sure, they've been fiddling with the colour grading, his eyes have been lit up and they've altered the background a little, but mark my words (be that Mark 3 or 5 or 6 or whatever he's up to now) this is a bit of creative reapplication.
Here's a still image from the Avengers trailer.
And here's the comparable one from Iron Man.
Look at the marks on the helmet and the "collar".
I'm prepared to bet this shot won't even be in the film, and it's been included here to provide a nice bit of Iron Man-ness, to set the tone – and boy, what an Iron Man tone the trailer has.
And there's also the extra advantage of it being an old asset, so the trailer team could have been working on its FX while Joss was still on set shooting the new Avengers material.
Or maybe it will be in the final film. I mean – IRONY ANVIL ALERT – if footage recycling is good enough for Michael Bay, then it's good enough for Joss Whedon.