I think this is a good step forward, so thanks to MtGox for effectively donating to the community the ID verification work they are doing.
The KYC requirements boil down to establishing a difficult-to-forge proof of identity. Is it really difficult to forge? I don't know, but it's better than nothing. The SSL Extended Verification certificate system is another example of such a scheme and EV SSL is certainly useful for Bitcoin merchants and companies to deploy (it gives you the green company name in the URL bar).
Erik is correct that that being identified does not imply the merchant will deliver on a transaction. I assume MtGox would not allow a company that repeatedly got bad reviews from customers to display the logo (I mean, linked to an entry on their website, obviously anyone can display a logo), but the second requirement to "have a minimum level of trust" is also a quite vague.
Whilst this program is a useful start, longer term the right solution is a proper implementation of
low-trust dispute mediation protocols. A dispute mediator could intervene on a transaction-by-transaction level, raising your trust in a given trade, without them needing to hold the coins (making them a tempting target for hacking).
Note that MtGox KYC federation and low-trust dispute mediation are complementary: dispute mediators operate in a market, but some may well require that the identities of companies for which they mediate have been verified, as a way to help them satisfactorily resolve disputes.