[yuliyp]

Having shares that have different rights is not really a new practice. For instance, it's what allows VCs to invest with more likelihood of recouping their investment, while still allowing for employees to get shares with a different payout structure. As long as these things are disclosed (and in Facebook's case they specifically call it out as a risk in the risks section of the annual report in a section titled "The dual class structure of our common stock and a voting agreement between certain stockholders have the effect of concentrating voting control with our CEO and certain other holders of our Class B common stock; this will limit or preclude your ability to influence corporate matters."

It's assumed that investors have a responsibility to read the information a company publishes for investors, so if someone were to invest blindly they'd only be hoodwinking themselves.