[uiri]

Seems that you are correct - earnings refers to profit (bottom line) rather than reveneu (top line). Thanks!

That being the case, DropBox probably isn't profitable yet which would throw their P/E through the roof and make that a useless metric.

Box is already public and it has revenue around $300 million and a valuation of ~$1.9B. DropBox will probably get a better revenue multiplier since their customer acquisition cost is lower than and their overall network effects and future outlook is better than Box. I'd place DropBox at a ~$6B valuation. Hopefully their revenue grows enough between now and IPO to support something closer to $10 or $12B.