Twitter set the price range for its IPO on Thursday, valuing its shares between $17 and $20. That would put the value of the company at about $10 billion, excluding options, the New York Times reports. With options and restricted stock units, it would be more like $12 billion. It's a conservative estimate, USA Today posits: "Pre-IPO trading of the company's shares suggested a valuation well in excess of $10.08 billion." But after that botched Facebook IPO, a bit of caution is probably in order.