There has been a lot of talk about unicorns lately, or, at least, I'm getting a nice Baader-Meinhof phenomenon for unicorns. At any rate, I think Aswath nicely illustrates some fuckery that can be done in valuation during an up round. It is nicely explained here:

http://aswathdamodaran.blogspot.com/2015/06/billion-dollar-tech-babies-blessing-of.html

And then there is this analysis of biotech unicorns and the idea that maybe it is better to invest in a basket rather than one:

http://mebfaber.com/2015/06/17/would-you-rather-own-the-unicorns-or-facebook/

In that article there is a link to a slideshare that, in fact comes from a bennedict evans post. You might as well check that out, too:

http://ben-evans.com/benedictevans/2015/6/15/us-tech-funding

fascinating stuff.