CONDENSED CONSOLIDATED BALANCE SHEETS (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Current Assets:
Cash and cash equivalents	$ 20,512	$ 14,572
Short-term investments	17,197	29,201
Accounts receivable	777	839
Due from related parties		75
Unbilled receivables	933	372
Inventory	3,624	3,204
Prepaid expenses and other current assets	710	692
Total current assets	43,753	48,955
Restricted cash	594	594
Property and equipment, net	1,120	1,358
Long-term investments		2,508
Other assets	95	95
Total assets	45,562	53,510
Current Liabilities:
Accounts payable	92	1,233
Accrued expenses	2,679	3,519
Current portion of deferred rent	165	165
Short-term deferred revenue	972	1,067
Total current liabilities	3,908	5,984
Deferred rent, net of current portion	14	55
Other long-term liabilities	134	131
Total liabilities	4,056	6,170
Commitments and contingencies (Note 10, 14)
Stockholders' Equity:
Preferred stock ($0.01 par value per share); 5,000,000 shares authorized; no shares issued or outstanding
Common stock ($0.01 par value per share); 100,000,000 shares authorized at March 31, 2013 and December 31, 2012, 34,365,227 and 34,306,570 shares issued and outstanding at March 31, 2013 and December 31, 2012, respectively	344	343
Additional paid-in capital	290,000	289,050
Accumulated other comprehensive loss	(43)	(21)
Accumulated deficit	(248,795)	(242,032)
Total stockholders' equity	41,506	47,340
Total liabilities and stockholders' equity	$ 45,562	$ 53,510