For some reason I missed the alert for this new paper on Native American genetics, luckily Andrew blogged on it yesterday.
Flora Jay et al., Predictions of Native American Population Structure Using Linguistic Covariates in a Hidden Regression Framework. PLoS ONE 2011. Open access.
The authors make an effort to compare autosomal genetic structure with linguistic and geographic groups with some success, producing this nice-looking map for the k=7 level of analysis:
Sadly it is becoming more and more common to show the readers only one level (the one the authors prefer) of the structure analysis instead of the whole sequence, this appears to be intended to avoid critical analysis from the readers, who might well find that, say, k=9 is more to their linking or explains stuff that k=7 does not.
I must mention this older paper (Sija Wang 2007), which reaches to similar results offering much more complete information in general.
I also remember another paper from that epoch (2006-07) which dug down to k=16 or something like that. But sadly I cannot find it right now.