The market cap isn't the stat to watch on BTC- the daily volume is. With volume at something in the low millions of dollars it'd be very easy for the currency to be manipulated by dollar-based traders. There's not much evidence that there are large deep pocketed investors who will toe som imaginary line in the wake of a retail investor sell-off. Until volumes pick up the daily price ont he various exchanges represents the valuations of a distressingly low number of traders.

That said, I think bitcoin is super exciting and want to see it succeed. But it needs to be much more heavily traded, regardless of its dollar exchange rate, for that to happen.