This is really big news because we probably can in nearest future understand much better the origin of present-day Europeans, thanks for new ancient East European samples. It is also sure that speculative flames will now go high, but I am not going to take a stance on this before I have the new data, especially regarding new Yamna culture samples. The reason to wait is that Haak et al. obviously uses same small and unclassified Finnish sample set than Lazaridis 2014 et al. Anyway, here is the link, Haak et al.
I am also running a big European wide analysis using Chromopainter and Finestucture in linked mode. It will be ready after two weeks or so. Link to the software: http://www.maths.bris.ac.uk/~madjl/finestructure-old/chromopainter.html