CONDENSED CONSOLIDATED BALANCE SHEETS (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Current Assets:
Cash and cash equivalents	$ 8,872	$ 14,572
Short-term investments	16,876	29,201
Accounts receivables	501	839
Due from related parties	91	75
Unbilled receivables	271	372
Inventory	3,400	3,204
Prepaid expenses and other current assets	932	692
Total current assets	30,943	48,955
Restricted cash	619	594
Property and equipment, net	891	1,358
Long-term investments		2,508
Other assets	50	95
Total assets	32,503	53,510
Current Liabilities:
Accounts payable	422	1,233
Accrued expenses	3,190	3,519
Current portion of deferred rent	97	165
Short-term deferred revenue	450	1,067
Other current liabilities	141
Total current liabilities	4,300	5,984
Deferred rent, net of current portion		55
Other long-term liabilities		131
Total liabilities	4,300	6,170
Commitments and contingencies (Note 10)
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 September 30, 2013 and December 31, 2012, 34,516,762 and 34,306,570 shares issued and outstanding at September 30, 2013 and December 31, 2012, respectively	345	343
Additional paid-in capital	291,828	289,050
Accumulated other comprehensive loss	(59)	(21)
Accumulated deficit	(263,911)	(242,032)
Total stockholders' equity	28,203	47,340
Total liabilities and stockholders' equity	$ 32,503	$ 53,510