Razib's post on the genetics of canids ("A map of charismatic canid genomic variation") does a nice summary of a recent paper in Genome Research, by vonHoldt and colleagues
Also, there's this:
Another interesting implication of the possibility of long term hybridization is that some of the distinctive alleles of extinct American wolf populations may now only be found in coyotes, since this species was much better at surviving human encroachment. And if wolves went extinct tomorrow, we could reconstruct them from what we find within coyotes Id think.
That gives me the chance to pull out my favorite quote from the famous evolutionary plant biologist G. Ledyard Stebbins
We inevitably reach the conclusion, therefore, that introgressive genotypes not only persist indefinitely, but that also, like polyploids, they can migrate far beyond the areas in which they originated, and can actually survive after the non-introgressed parental species has become extinct.
Theories that predict unknown facts before they can be observed are like uncut diamonds.