| Cash and cash equivalents | |
| Investment securities, available-for-sale | |
| Prepaid expenses, receivables and other current assets | |
| Total current assets | |
| Property and equipment, net | |
| Other assets | |
| Total assets | |
| Accounts payable | |
| Accrued expenses | |
| Current portion of deferred revenue | |
| Current portion of long-term debt | |
| Total current liabilities | |
| Long-term portion of deferred revenue | |
| Other long-term liabilities | |
| Total liabilities | |
| Commitments (Note 9) | |
| Preferred stock, $0.0001 par value; 5,000,000 shares authorized at June 30, 2011 and December 31, 2010; no shares issued and outstanding at June 30, 2011 and December 31, 2010 | |
| Common stock, $0.0001 par value; 150,000,000 shares and 75,000,000 shares authorized at June 30, 2011 and December 31, 2010, respectively; 52,799,606 shares and 39,350,561 shares issued and outstanding at June 30, 2011 and December 31, 2010, respectively | |
| Additional paid-in capital | |
| Accumulated deficit | |
| Accumulated other comprehensive income | |
| Total stockholders' equity | |
| Total liabilities and stockholders' equity |