The Wikipedia entry for "Asylum of the Daleks" says:
... Whether Coleman's later character is the same as Oswin has yet to be confirmed. ...
But people have also pointed out that Moffat had denied that Jenna-Louise Coleman would appear before the Christmas Special, so Moffat, like the Doctor, lies.
It would seem difficult to bring her in as a companion, but ignore her earlier appearance altogether. Some have suggested that she could either appear as an ancestor of Souffle Girl, or possibly could appear from earlier in her own time line (albeit that then requires her to have forgotten about this somehow, before appearing on the Asylum Planet).
It'll be interesting to see what they do. I suspect they'll be a bit more imaginative than any of those suggestions, both of which seem a little predictable.
Apparently there were around 25 different types of Dalek in that episode, being extracted from pretty much every previous appearance that they had made over all the preceding series!