Wow. That's really interesting news. They raised $1bn in the IPO. Their current assets have dropped from $2bn at the time of the IPO to $1.4bn today -- so half a year. Balance sheet: http://www.bloomberg.com/quote/ZNGA:US/balance-sheet

[edit] They did buy their HQ though for $250MM, which explains some of the transfer of short term to long term assets.