CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Operating activities
Net loss	$ (10,252)	$ (8,834)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	167	208
Stock-based compensation	713	542
Changes in revaluation of warrant liability	5,073	4,461
Non-cash interest expense	4	6
Deferred income taxes	7	0
Loss on disposal	56	0
Changes in operating assets and liabilities, net of effects of acquired business:
Accounts receivable	(289)	1,074
Inventories	(1,624)	(2,467)
Other assets	910	(124)
Accounts payable	(3,299)	(530)
Accrued liabilities	85	1,674
Deferred revenue	97	86
Net cash used in operating activities	(8,352)	(3,904)
Investing activities
Purchases of furniture, equipment and leasehold improvements	(26)	(2)
Purchases of certain other assets	0	(2)
Maturities of investments	0	200
Net cash provided by (used in) investing activities	(26)	196
Financing activities
Net proceeds from equity incentive plans	152	77
Net proceeds from public offering	51,502	9,612
Proceeds from revolving line of credit	526	0
Payments on debt, revolving line of credit and landlord provided leasehold incentives	(1,335)	(29)
Net cash provided by financing activities	50,845	9,660
Net increase in cash and cash equivalents	42,467	5,952
Cash and cash equivalents, beginning of period	26,696	25,497
Cash and cash equivalents, end of period	69,163	31,449
Supplemental disclosures:
Cash paid for interest	78	83
Cash paid for income taxes	$ 26	$ 10