It won't be possible to revive extinct species anytime soon, but I don't think it's a hopeless project at all to prepare for a day when it might be possible.
Perhaps see: Extinct ibex is resurrected by cloning
It says: "An extinct animal has been brought back to life for the first time after being cloned from frozen tissue."
It was only alive for seven minutes, but it's something.
Interesting recent article from Ben-Nun et al. (doi:10.1038/nmeth.1706) in the high-impact journal Nature Methods.
As I understand it, they express reprogramming factors in the adult cells (e.g., fibroblasts) of two endangered species (here and here) to convert them into induced pluripotent stem cells.
They then cryopreserve these pluripotent stem cells, in the hopes that they can eventually be used to increase the number and genetic diversity of these two species.
However, this will require two additional technologies which, crucially, are still in development:
1) the generation of germ cells from pluripotent stem cells, and
2) the development of assisted reproductive technologies for related monkeys and rhinos.
In the meantime, these pluripotent stem cells will simply remain in cryopreservation.
What does this remind you of? In what ways is it different, such that it can be published in a high status journal? Are those differences informative in any way?