If I had that kind of cash, I think I'd probably turn toward angel investing as well. It seems that returns can be significantly higher that most stock transactions.
However, you did see how Google stock skyrocketed after their IPO; Facebook will (I think) do the same, so it's likely a good investment but I certainly wouldn't sink my life savings.
Its always better to invest in multiple areas. One is Angel investing (check with PG if he is willing to join you as YC partner :), one might be stocks of Google/AAPL (if I were you), Gold and some charity(increase your positive life Karma..as we call it in India)
However, you did see how Google stock skyrocketed after their IPO; Facebook will (I think) do the same, so it's likely a good investment but I certainly wouldn't sink my life savings.
Hell, I just wish I had savings at all!