I haven't seen a single discussion of Bitcoin as a currency, it's always an investment. I asked someone a few days ago about how much is actually being spent and they linked me to a list of transactions but they all seemed to be either SatoshiDice or really low amounts, are there any statistics on who is actually spending Bitcoins on products and/or services unrelated to Bitcoins? I saw reddit mentioned that the volume of Bitcoin transactions they have (on reddit gold) is so low they're losing money and that's a site that has a big community of Bitcoin users / supporters.
What happens when a government decides enough is enough and buys then dumps BTC? It wouldn't take much capital to cause a bank run type of inflation attack.
Fixed that for you. Those reasons are all much older than this sudden jump in value. Even if they weren't old, there's no way they're pumping the value of Bitcoin by 500%. If something's too good to be true, it probably is.