CONSOLIDATED BALANCE SHEETS (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Current Assets:
Cash and cash equivalents	$ 14,572	$ 21,277
Short-term investments	29,201	55,578
Accounts receivable	839	146
Due from related parties	75	311
Unbilled receivables	372	304
Prepaid expenses and other current assets	692	823
Inventory	3,204
Total current assets	48,955	78,439
Restricted cash	594	622
Property and equipment, net	1,358	2,276
Long-term investments	2,508	1,503
Other assets	95	72
Total assets	53,510	82,912
Current Liabilities:
Accounts payable	1,233	512
Accrued expenses	3,519	3,574
Current portion of deferred rent	165	165
Short-term deferred revenue	1,067	2,914
Total current liabilities	5,984	7,165
Deferred rent, net of current portion	55	221
Long-term deferred revenue		35,944
Other long-term liabilities	131	119
Total liabilities	6,170	43,449
Commitments and contingencies (Note 7)
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 December 31, 2012 and 2011, 34,306,570 and 34,115,798 shares issued and outstanding at December 31, 2012 and 2011, respectively	343	341
Additional paid-in capital	289,050	284,796
Accumulated other comprehensive loss	(21)	(12)
Accumulated deficit	(242,032)	(245,662)
Total stockholders' equity	47,340	39,463
Total liabilities and stockholders' equity	$ 53,510	$ 82,912