1.16 billion of capital and 140 employees
6.0-7.0 billion valuation, estimated
In terms of profit per employee, you're looking at 50 to 100 million to 'break even' at that vauation
So, part of it is the $$ raised and part is the $$ valuation
Is it possible paint yourself into a box, strategically, if you take money at aggressive valuation?
Source: http://www.crunchbase.com/company/twitter
Edit: Headcount data look out of date at TechCrunch. See comment below, this now ~1,000 not 140.