A Deus Ex Machina resolution is one that is from factors external to the established plot. If Captain Jack Harkness had beamed in at the last moment with a spare set of time bracelets and said "Hello guys and girls, anyone want a ride?", that would have been a Deus Ex Machina.
The resolution to this episode arose naturally from the characters' actions and the previously-established facts. I certainly didn't anticipate it in advance, but the moment the Doctor began his countdown and I realised that he did, in fact, have a plan, my immediate thought was "ooh, the sewer-daleks!"
On another note, does anyone else think that this isn't the last we've heard of "the Hybrid"? Davros assumed that the ancient Time Lord legend of two warrior races brought together to create a third, even stronger one must refer to the Time Lords and the Daleks, but I'm guessing there may actually be different candidates involved.
I wouldn't be surprised if this becomes a running theme for this season.