I had the impression the roadmap called for a BitDNS-like decentralized mapping system, since Gavin asked to map "strings" to addresses. Maybe I misunderstood.
In my head I was imagining a way of telling bitcoin to subscribe to some service(s) that did the mapping-- maybe a setting in the GUI where you could specify "use these six services, in this order, to try to resolve bitcoin addresses that aren't plain-old-bitcoin-addresses." With the services specified by name+URL (and some standard REST-ful protocol was defined for mapping string to bitcoin address). Or maybe name+pattern+URL.
I haven't looked at genjix' patch, and haven't thought deeply about security issues-- but I bet there are lots...