Actual link (grrr):
<a href="http://code.mixpanel.com/2011/08/05/how-and-why-we-switched-from-erlang-to-python/" rel="nofollow">http://code.mixpanel.com/2011/08/05/how-and-why-we-switched-...</a>
"However, the team lacked an Erlang expert and the code became difficult to manage over time"<p>So I guess they had decided to go for Erlang because they had the expert ;)