Unfortunately, Mt. Gox faces no regulation, so their data should be treated like the data from an offshore online poker company (many of which scammed users in underhanded ways even when they stood to gain significantly from their legitimate transaction fees). There would be almost no indication to the public until it were too late if Mt. Gox were actually directly a Ponzi scheme, even if the rest of the Bitcoin system were honest (which it is not).
I'd also be afraid of having my assets frozen if I transferred money to and from Mt. Gox or the other exchanges. To use Britcoin, for example, you need to send and receive money from an individual developer -- that is, from his individual account. There's not necessarily protection for his transferees if it turns out that he, willingly or not, was engaging in money laundering.
One additional thing that bothers me about the Bitcoin "community" at present is that they are engaged in an active and deceptive attempt to sanitize their public image. For example, in a Gawker story about drugs, Jeff Garzik, a core developer, inaccurately commented that Bitcoin could not be used to purchase anything anonymously. He surely knows that it wouldn't be difficult to do so; he appears simply to have been underplaying a regulatory risk that the currency faces in order to get part of the public on his side.
Bitcoin == marketing. It has very good marketing on its side, even if the marketing is in some sense "open source" and communal. In that sense, it's very interesting sociologically. But it's, at core, a deception in practice.