I like the the low friction of mtgox but if libertyreserve.com is down, doesn't that mean that your dollars are stuck in a mtgox account?

I've seen a few sites that offer to convert small quantities (5 BTC) into online-only credit cards, but most of them have a lot of friction ($5 fee+%)

The bitcoin wiki lists quite a few exchanges, but many of them seem very very dodgy. Is there any reputational system that has emerged to know whether or not an exchange can be trusted?

Thanks,
gofasterplease