Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010
Cash flow from operating activities:
Net loss	$ (20,965)	$ (19,175)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	1,234	1,549
Stock-based compensation and 401(k) match	1,364	1,634
Fair value adjustment of common stock warrants	(3,560)	(6,422)
Loss / (Gain) on sale of equipment	45	(16)
Changes in:
Prepaid expenses and other current assets	(157)	(52)
Accounts payable	(574)	391
Accrued expenses	(314)	(166)
Other assets	174	4
Other liabilities and accrued interest on loan payable	55	(2,017)
Net cash used in operating activities	(22,698)	(24,270)
Cash flow from investing activities:
Purchase of property and equipment	(106)	(101)
Net cash used in investing activities	(106)	(101)
Cash flow from financing activities:
Proceeds from issuance of securities, net of expenses	22,927	27,977
Principal payments of loan payable	0	(8,500)
Principal payments under equipment loan and capital lease obligations	(145)	(636)
Net cash provided by financing activities	22,782	18,841
Net decrease in cash and cash equivalents	(22)	(5,530)
Cash and cash equivalents - beginning of year	10,211	15,741
Cash and cash equivalents - end of year	10,189	10,211
Supplementary disclosure of cash flows information:
Interest paid	20	2,123
Non-cash transactions:
Equipment acquired through capitalized lease	$ 0	$ 48