Aerial rooting was a phenomenon that we observed in 2007 in many vineyards across Oklahoma.  I also saw it in a few locations in 2009.  I remember back in 2007 there was quite a bit of worry about what they meant for the vines.  At OSU we did a study on our Perkins vineyard to look at the effects of the rooting on the vine.  The results were recently published in the Journal of the American Journal of Enology and Viticulture.  You can access the abstract of the article here:

Usually I post my articles on the OSU Viticulture website, but due to copyright issues I cannot post this article yet.  However, I have a pdf copy of the entire paper.  If you would like to read it and see tables of data, etc. drop me a comment here or send an email and I will send you a copy.