Figured some people might be interested in this:

Y-axis is correlation, X-axis is the days. That is, day 1 is the first day that both ETH and XMR were trading on Poloniex.
The chart uses a 30 day correlation rolling window.
Correlation for dummies ->
http://www.investopedia.com/terms/c/correlation.aspFor what it's worth, the correlation over the whole trading history is ~0.15.